Release v0.1.0-beta.2

- Use X | None syntax instead of Optional[X] (UP045)
- Sort imports in dashboard app (I001)
- Remove unnecessary UTF-8 encoding argument (UP012)
- Add 'from err' to exception re-raises (B904)
- Remove unused imports in integration tests (F401)
- Fix useless expression in test (B018)
- Cast **1.5 result to float in LDO model (mypy no-any-return)
- Use functools.partial instead of lambda in server (mypy misc)

CHANGELOG.md

@@ -7,6 +7,78 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.1.0-beta.2] - 2025-12-03
+
+### Added
+- Test Executive Framework (Sprint 14)
+  - TestContext dataclass providing runtime context for tests
+  - ITest abstract base class defining test interface
+  - TestLogger for recording measurements, results, and events
+  - LimitChecker for evaluating pass/fail against specification limits
+  - TestRunner for orchestrating test execution
+  - SQLite-based TestRepository for persisting test data
+  - Parquet measurement storage for efficient time-series data
+- DVT Test Implementation (Sprint 15)
+  - BaseDVTTest providing common test utilities
+  - TempCo characterisation test (temperature coefficient measurement)
+  - Temperature sweep with automatic thermal settling
+  - Linear regression TempCo calculation (ppm/°C)
+  - Comprehensive integration tests for end-to-end validation
+
+### Technical
+- Test framework supports data logging, limit evaluation, and result persistence
+- TempCo test demonstrates full end-to-end workflow: configure instruments → sweep temperature → measure → calculate → evaluate
+- All framework and test components fully type-checked and linted
+
+## [0.1.0-beta.1] - 2025-12-02
+
+### Added
+- Hardware Abstraction Layer (HAL) with instrument interface protocols
+  - IThermalChamber protocol with temperature control methods
+  - IPowerSupply protocol with voltage/current control and measurement
+  - IMultimeter protocol with DC voltage, current, and resistance measurement
+- Instrument drivers implementing HAL interfaces
+  - ThermalChamberDriver implements IThermalChamber
+  - PowerSupplyDriver implements IPowerSupply
+  - MultimeterDriver implements IMultimeter
+- Instrument factory pattern for backend abstraction
+  - InstrumentSet dataclass containing chamber, PSU, and DMM
+  - InstrumentConfig for specifying backend (simulator/pyvisa) and connection details
+  - InstrumentFactory.create() for creating instrument sets from configuration
+- Transport layer abstraction
+  - Transport ABC defining connect/disconnect/read/write/query interface
+  - TCPTransport implementation for TCP/IP connections
+- Comprehensive test suite for HAL (16 tests)
+  - Interface implementation verification
+  - Factory pattern testing with mocked backends
+  - Configuration validation
+
+### Changed
+- Drivers now explicitly inherit from interface ABCs for maximum type safety
+- Moved InstrumentServer to instruments/transport for better architecture
+
+### Technical
+- ABC-based interfaces ensure compile-time interface compliance
+- Factory pattern enables seamless switching between simulated and real hardware
+- All HAL components fully type-checked with mypy strict mode
+
+## [0.1.0-alpha.3] - 2025-12-02
+
+### Added
+- Async TCP server for exposing virtual instruments over network
+- InstrumentServer class with multi-port, multi-client support
+- Line-based SCPI protocol (newline-terminated commands/responses)
+- SimulationServer wiring physics engine to all virtual instruments
+- CLI `serve` command to start simulation server with configurable ports
+- Integration tests for TCP server and instrument connectivity
+
+### Infrastructure
+- SCPI foundation (Sprint 5): command parser with IEEE 488.2 support
+- Virtual instrument base class with command dispatch
+- Thermal chamber simulator (TEMP:SETPOINT, TEMP:ACTUAL?, TEMP:STAB?)
+- Power supply simulator (VOLT, CURR, OUTP, MEAS commands)
+- Multimeter simulator (MEAS:VOLT:DC?, MEAS:CURR:DC?, CONF, READ?)
+
 ## [0.1.0-alpha.2] - 2025-12-02
 
 ### Added
@@ -57,9 +129,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 | Version | Date | Milestone |
 |---------|------|-----------|
 | 0.1.0 | TBD | MVP Complete |
-| 0.1.0-beta.2 | TBD | First DVT test runs |
+| 0.1.0-beta.2 | 2025-12-03 | First DVT test runs |
-| 0.1.0-beta.1 | TBD | HAL complete |
+| 0.1.0-beta.1 | 2025-12-02 | HAL complete |
-| 0.1.0-alpha.3 | TBD | Network ready |
+| 0.1.0-alpha.3 | 2025-12-02 | Network ready |
 | 0.1.0-alpha.2 | 2025-12-02 | Visual demo |
 | 0.1.0-alpha.1 | 2025-12-02 | Physics engine |
 | 0.0.1 | 2025-12-01 | Project scaffolding |

config/default.yaml

@@ -0,0 +1,149 @@
+# py_dvt_ate Default Configuration
+# This file contains default settings for the DVT simulation platform.
+# Copy this file and modify values as needed for your environment.
+
+# =============================================================================
+# Instrument Configuration
+# =============================================================================
+instruments:
+  # Backend selection: "simulator" or "pyvisa"
+  # - simulator: Use virtual instruments with physics simulation (for development)
+  # - pyvisa: Connect to real instruments via PyVISA (for production testing)
+  backend: simulator
+
+  # Simulator backend configuration
+  # Used when backend=simulator. Virtual instruments are exposed as TCP servers.
+  simulator:
+    host: localhost
+    thermal_chamber_port: 5001
+    power_supply_port: 5002
+    multimeter_port: 5003
+
+  # PyVISA backend configuration
+  # Used when backend=pyvisa. Provide VISA resource strings for real instruments.
+  # Example: "TCPIP::192.168.1.10::5001::SOCKET"
+  pyvisa:
+    thermal_chamber: null
+    power_supply: null
+    multimeter: null
+
+# =============================================================================
+# Physics Simulation Parameters
+# =============================================================================
+physics:
+  # Physics engine update rate (Hz)
+  # Higher rates provide better accuracy but use more CPU.
+  update_rate_hz: 100.0
+
+  # Thermal model parameters
+  thermal:
+    # Chamber thermal time constant (seconds)
+    # Time for chamber temperature to reach 63% of final value
+    chamber_time_constant_s: 30.0
+
+    # DUT case thermal time constant (seconds)
+    # Time for case temperature to reach 63% of final value
+    case_time_constant_s: 5.0
+
+    # Junction-to-case thermal resistance (°C/W)
+    # How much the junction heats above case per watt dissipated
+    theta_jc: 15.0
+
+    # Case-to-ambient thermal resistance (°C/W)
+    # How much the case heats above ambient per watt dissipated
+    theta_ca: 5.0
+
+  # Thermal chamber behaviour
+  chamber:
+    # Maximum temperature ramp rate (°C/min)
+    # Real chambers have limited heating/cooling rates
+    ramp_rate_c_per_min: 10.0
+
+    # Temperature stability window (°C)
+    # Chamber is considered stable when within ±this value of setpoint
+    stability_window_c: 0.5
+
+    # Stability duration requirement (seconds)
+    # Chamber must remain in stability window for this duration
+    stability_time_s: 30.0
+
+# =============================================================================
+# DUT (Device Under Test) Configuration
+# =============================================================================
+dut:
+  # DUT model type
+  # Currently supported: "ldo"
+  model: ldo
+
+  # DUT model parameters
+  parameters:
+    # Nominal output voltage at 25°C (V)
+    nominal_output_voltage: 3.3
+
+    # Temperature coefficient (ppm/°C)
+    # Voltage change per degree: ΔV = V₀ × tempco × ΔT / 1e6
+    tempco_ppm_per_c: 50.0
+
+    # Quiescent current at 25°C (µA)
+    quiescent_current_ua: 50.0
+
+    # Quiescent current temperature coefficient (per °C)
+    # Iq change per degree: ΔIq = Iq₀ × tempco × ΔT
+    quiescent_current_tempco: 0.003
+
+    # Dropout voltage (V)
+    # Minimum Vin-Vout differential for regulation
+    dropout_voltage: 0.3
+
+# =============================================================================
+# Data Storage Configuration
+# =============================================================================
+data:
+  # SQLite database path for test runs and results
+  database_path: ./data/py_dvt_ate.db
+
+  # Directory for measurement data files (Parquet format)
+  measurements_dir: ./data/measurements
+
+  # Directory for generated reports (PDF, HTML)
+  reports_dir: ./data/reports
+
+# =============================================================================
+# Logging Configuration
+# =============================================================================
+logging:
+  # Logging level: DEBUG, INFO, WARNING, ERROR, CRITICAL
+  level: INFO
+
+  # Log file path
+  # Use null to disable file logging
+  file: ./data/logs/py_dvt_ate.log
+
+  # Log message format
+  # Uses Python logging format strings
+  format: "%(asctime)s - %(name)s - %(levelname)s - %(message)s"
+
+# =============================================================================
+# Dashboard Configuration (Streamlit)
+# =============================================================================
+dashboard:
+  # Enable/disable the Streamlit dashboard
+  enabled: true
+
+  # Dashboard server port
+  port: 8501
+
+# =============================================================================
+# API Configuration (Phase 2)
+# =============================================================================
+api:
+  # Enable/disable the REST API server
+  # Currently not implemented (Phase 2 feature)
+  enabled: false
+
+  # API server host
+  # Use "0.0.0.0" to listen on all interfaces
+  host: "0.0.0.0"
+
+  # API server port
+  port: 8000

docs/02_technical_specification.md

@@ -450,109 +450,123 @@ High-level call → Driver → SCPI command → Transport → Instrument
 ```python
 # py_dvt_ate/instruments/interfaces.py
 
-from typing import Protocol, runtime_checkable
+from abc import ABC, abstractmethod
 
 
 @runtime_checkable
-class IThermalChamber(Protocol):
+class IThermalChamber(ABC):
     """Hardware abstraction for thermal chambers."""
 
+    @abstractmethod
     def set_temperature(self, setpoint: float) -> None:
-        """Set target temperature in degrees Celsius."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def get_temperature(self) -> float:
-        """Get current actual temperature in degrees Celsius."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def get_setpoint(self) -> float:
-        """Get current temperature setpoint."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def is_stable(self) -> bool:
-        """Check if temperature has stabilised at setpoint."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def wait_until_stable(
         self,
         timeout: float = 300.0,
         poll_interval: float = 1.0
     ) -> bool:
-        """
+        """[docstring]"""  
-        Block until temperature stabilises or timeout.
+        pass
-
-        Returns:
-            True if stable, False if timeout
-        """
-        ...
 
+    @abstractmethod
     def set_ramp_rate(self, rate: float) -> None:
-        """Set temperature ramp rate in degrees C per minute."""
+        """[docstring]"""  
-        ...
+        pass
 
 
 @runtime_checkable
-class IPowerSupply(Protocol):
+class IPowerSupply(ABC):
     """Hardware abstraction for programmable power supplies."""
 
+    @abstractmethod
     def set_voltage(self, channel: int, voltage: float) -> None:
-        """Set output voltage for specified channel."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def get_voltage(self, channel: int) -> float:
-        """Get voltage setpoint for specified channel."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def set_current_limit(self, channel: int, current: float) -> None:
-        """Set current limit for specified channel."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def get_current_limit(self, channel: int) -> float:
-        """Get current limit for specified channel."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def measure_voltage(self, channel: int) -> float:
-        """Measure actual output voltage."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def measure_current(self, channel: int) -> float:
-        """Measure actual output current."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def enable_output(self, channel: int, enable: bool) -> None:
-        """Enable or disable channel output."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def is_output_enabled(self, channel: int) -> bool:
-        """Check if channel output is enabled."""
+        """[docstring]"""  
-        ...
+        pass
 
 
 @runtime_checkable
-class IMultimeter(Protocol):
+class IMultimeter(ABC):
     """Hardware abstraction for digital multimeters."""
 
+    @abstractmethod
     def measure_dc_voltage(self, range: str = "AUTO") -> float:
-        """Measure DC voltage. Range: AUTO, 0.1, 1, 10, 100, 1000."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def measure_dc_current(self, range: str = "AUTO") -> float:
-        """Measure DC current."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def measure_resistance(self, range: str = "AUTO") -> float:
-        """Measure resistance."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def set_integration_time(self, nplc: float) -> None:
-        """Set integration time in power line cycles (0.1 to 100)."""
+        """[docstring]"""  
-        ...
+        pass
 
 
 @runtime_checkable
-class ITestLogger(Protocol):
+class ITestLogger(ABC):
     """Abstraction for test data logging."""
 
+    @abstractmethod
     def log_measurement(
         self,
         parameter: str,
@@ -560,9 +574,10 @@ class ITestLogger(Protocol):
         unit: str,
         conditions: dict[str, float] | None = None
     ) -> None:
-        """Log a single measurement."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def log_result(
         self,
         parameter: str,
@@ -571,12 +586,13 @@ class ITestLogger(Protocol):
         lower_limit: float | None = None,
         upper_limit: float | None = None
     ) -> None:
-        """Log a test result with optional limits."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def log_event(self, message: str, level: str = "INFO") -> None:
-        """Log a test event or message."""
+        """[docstring]"""  
-        ...
+        pass
 ```
 
 ### 4.2 Transport Interface
@@ -584,36 +600,42 @@ class ITestLogger(Protocol):
 ```python
 # py_dvt_ate/instruments/transport/base.py
 
-from typing import Protocol
+from abc import ABC, abstractmethod
 
 
-class Transport(Protocol):
+class Transport(ABC):
     """Abstract transport interface for instrument communication."""
 
+    @abstractmethod
     def connect(self) -> None:
-        """Establish connection to instrument."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def disconnect(self) -> None:
-        """Close connection to instrument."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def write(self, command: str) -> None:
-        """Send command to instrument."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def read(self, timeout: float | None = None) -> str:
-        """Read response from instrument."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def query(self, command: str, timeout: float | None = None) -> str:
-        """Send command and read response."""
+        """[docstring]"""  
-        ...
+        pass
 
     @property
+    @abstractmethod
     def is_connected(self) -> bool:
-        """Check if connection is active."""
+        """[docstring]"""  
-        ...
+        pass
 ```
 
 ### 4.3 Test Interface
@@ -624,7 +646,7 @@ class Transport(Protocol):
 from dataclasses import dataclass, field
 from datetime import datetime
 from enum import Enum
-from typing import Protocol
+from abc import ABC, abstractmethod
 from uuid import UUID
 
 
@@ -675,22 +697,25 @@ class TestContext:
     config: dict
 
 
-class ITest(Protocol):
+class ITest(ABC):
     """Interface for test implementations."""
 
     @property
+    @abstractmethod
     def name(self) -> str:
-        """Test name identifier."""
+        """[docstring]"""  
-        ...
+        pass
 
     @property
+    @abstractmethod
     def description(self) -> str:
-        """Human-readable test description."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def execute(self, context: TestContext) -> TestStatus:
-        """Execute the test, return status."""
+        """[docstring]"""  
-        ...
+        pass
 ```
 
 ### 4.4 Factory Interface
@@ -1173,30 +1198,34 @@ Schema:
 ```python
 # py_dvt_ate/data/repository.py (interface)
 
-from typing import Protocol
+from abc import ABC, abstractmethod
 from uuid import UUID
 
 
-class ITestRepository(Protocol):
+class ITestRepository(ABC):
     """Repository interface for test data."""
 
+    @abstractmethod
     def create_run(
         self,
         test_name: str,
         config: dict,
         operator: str | None = None
     ) -> UUID:
-        """Create a new test run, return its ID."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def update_run_status(self, run_id: UUID, status: str) -> None:
-        """Update test run status."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def complete_run(self, run_id: UUID, status: str) -> None:
-        """Mark test run as complete with final status."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def save_result(
         self,
         run_id: UUID,
@@ -1206,28 +1235,32 @@ class ITestRepository(Protocol):
         lower_limit: float | None = None,
         upper_limit: float | None = None
     ) -> None:
-        """Save a test result."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def save_measurements(
         self,
         run_id: UUID,
         measurements: list["Measurement"]
     ) -> None:
-        """Save batch of measurements to Parquet."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def get_run(self, run_id: UUID) -> "TestRun":
-        """Get test run by ID."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def get_results(self, run_id: UUID) -> list["TestResult"]:
-        """Get all results for a test run."""
+        """[docstring]"""  
-        ...
+        pass
 
+    @abstractmethod
     def get_measurements_dataframe(self, run_id: UUID):
-        """Get measurements as pandas DataFrame."""
+        """[docstring]"""  
-        ...
+        pass
 ```
 
 ---

pyproject.toml

@@ -37,6 +37,7 @@ dev = [
     "pytest-asyncio>=0.21",
     "ruff>=0.1",
     "mypy>=1.0",
+    "types-PyYAML>=6.0",
 ]
 
 [project.scripts]
@@ -86,5 +87,8 @@ ignore_missing_imports = true
 
 [tool.pytest.ini_options]
 testpaths = ["tests"]
-asyncio_mode = "auto"
 addopts = "-v --tb=short"
+
+[tool.pytest-asyncio]
+mode = "auto"
+default_fixture_loop_scope = "function"

src/py_dvt_ate/__init__.py

@@ -1,3 +1,3 @@
 """py_dvt_ate: Coupled Physics DVT Simulation Platform."""
 
-__version__ = "0.1.0-alpha.2"
+__version__ = "0.1.0-beta.2"

src/py_dvt_ate/app/cli.py

@@ -1,6 +1,6 @@
 """Command-line interface for py_dvt_ate."""
 
-from typing import Annotated, Optional
+from typing import Annotated
 
 import typer
 
@@ -23,7 +23,7 @@ def version_callback(value: bool) -> None:
 @app.callback()
 def main(
     version: Annotated[
-        Optional[bool],
+        bool | None,
         typer.Option(
             "--version",
             "-v",
@@ -36,5 +36,52 @@ def main(
     """py-dvt-ate: Coupled Physics DVT Simulation Platform."""
 
 
+@app.command()
+def serve(
+    host: Annotated[
+        str,
+        typer.Option("--host", "-h", help="Host address to bind to."),
+    ] = "127.0.0.1",
+    chamber_port: Annotated[
+        int,
+        typer.Option("--chamber-port", help="Port for thermal chamber instrument."),
+    ] = 5000,
+    psu_port: Annotated[
+        int,
+        typer.Option("--psu-port", help="Port for power supply instrument."),
+    ] = 5001,
+    dmm_port: Annotated[
+        int,
+        typer.Option("--dmm-port", help="Port for multimeter instrument."),
+    ] = 5002,
+    physics_rate: Annotated[
+        float,
+        typer.Option("--physics-rate", help="Physics engine update rate in Hz."),
+    ] = 100.0,
+) -> None:
+    """Start the simulation server with virtual instruments.
+
+    Runs a TCP server hosting virtual SCPI instruments connected to a
+    shared physics engine. Each instrument listens on its own port.
+    """
+    from py_dvt_ate.simulation.server import main as run_server
+
+    typer.echo(f"Starting simulation server on {host}...")
+    typer.echo(f"  Thermal chamber: port {chamber_port}")
+    typer.echo(f"  Power supply:    port {psu_port}")
+    typer.echo(f"  Multimeter:      port {dmm_port}")
+    typer.echo(f"  Physics rate:    {physics_rate} Hz")
+    typer.echo("")
+    typer.echo("Press Ctrl+C to stop.")
+
+    run_server(
+        host=host,
+        chamber_port=chamber_port,
+        psu_port=psu_port,
+        dmm_port=dmm_port,
+        physics_rate=physics_rate,
+    )
+
+
 if __name__ == "__main__":
     app()

src/py_dvt_ate/app/config.py

@@ -0,0 +1,200 @@
+"""Configuration models for py_dvt_ate.
+
+This module defines Pydantic models for all configuration sections.
+Configuration can be loaded from YAML files and validated at runtime.
+"""
+
+import os
+from pathlib import Path
+from typing import Any, Literal
+
+import yaml
+from pydantic import BaseModel, Field
+
+
+class SimulatorConfig(BaseModel):
+    """Configuration for simulator instrument backend."""
+
+    host: str = "localhost"
+    thermal_chamber_port: int = 5001
+    power_supply_port: int = 5002
+    multimeter_port: int = 5003
+
+
+class PyVISAConfig(BaseModel):
+    """Configuration for PyVISA instrument backend."""
+
+    thermal_chamber: str | None = None
+    power_supply: str | None = None
+    multimeter: str | None = None
+
+
+class InstrumentsConfig(BaseModel):
+    """Instrument backend configuration."""
+
+    backend: Literal["simulator", "pyvisa"] = "simulator"
+    simulator: SimulatorConfig = Field(default_factory=SimulatorConfig)
+    pyvisa: PyVISAConfig = Field(default_factory=PyVISAConfig)
+
+
+class ThermalConfig(BaseModel):
+    """Thermal physics parameters."""
+
+    chamber_time_constant_s: float = 30.0
+    case_time_constant_s: float = 5.0
+    theta_jc: float = 15.0  # °C/W (junction to case)
+    theta_ca: float = 5.0  # °C/W (case to ambient)
+
+
+class ChamberConfig(BaseModel):
+    """Thermal chamber behaviour parameters."""
+
+    ramp_rate_c_per_min: float = 10.0
+    stability_window_c: float = 0.5
+    stability_time_s: float = 30.0
+
+
+class PhysicsConfig(BaseModel):
+    """Physics simulation parameters."""
+
+    update_rate_hz: float = 100.0
+    thermal: ThermalConfig = Field(default_factory=ThermalConfig)
+    chamber: ChamberConfig = Field(default_factory=ChamberConfig)
+
+
+class DUTParameters(BaseModel):
+    """DUT model parameters."""
+
+    nominal_output_voltage: float = 3.3
+    tempco_ppm_per_c: float = 50.0
+    quiescent_current_ua: float = 50.0
+    quiescent_current_tempco: float = 0.003
+    dropout_voltage: float = 0.3
+
+
+class DUTConfig(BaseModel):
+    """DUT model configuration."""
+
+    model: str = "ldo"
+    parameters: DUTParameters = Field(default_factory=DUTParameters)
+
+
+class DataConfig(BaseModel):
+    """Data storage paths."""
+
+    database_path: str = "./data/py_dvt_ate.db"
+    measurements_dir: str = "./data/measurements"
+    reports_dir: str = "./data/reports"
+
+
+class LoggingConfig(BaseModel):
+    """Logging configuration."""
+
+    level: str = "INFO"
+    file: str = "./data/logs/py_dvt_ate.log"
+    format: str = "%(asctime)s - %(name)s - %(levelname)s - %(message)s"
+
+
+class DashboardConfig(BaseModel):
+    """Dashboard (Streamlit) configuration."""
+
+    enabled: bool = True
+    port: int = 8501
+
+
+class APIConfig(BaseModel):
+    """API server configuration (Phase 2)."""
+
+    enabled: bool = False
+    host: str = "0.0.0.0"
+    port: int = 8000
+
+
+class AppConfig(BaseModel):
+    """Root configuration model."""
+
+    instruments: InstrumentsConfig = Field(default_factory=InstrumentsConfig)
+    physics: PhysicsConfig = Field(default_factory=PhysicsConfig)
+    dut: DUTConfig = Field(default_factory=DUTConfig)
+    data: DataConfig = Field(default_factory=DataConfig)
+    logging: LoggingConfig = Field(default_factory=LoggingConfig)
+    dashboard: DashboardConfig = Field(default_factory=DashboardConfig)
+    api: APIConfig = Field(default_factory=APIConfig)
+
+
+def _apply_env_overrides(config_dict: dict[str, Any]) -> None:
+    """Apply environment variable overrides to config dictionary.
+
+    Environment variables follow the pattern: PYDVTATE__{SECTION}__{KEY}
+    For nested keys, use double underscores: PYDVTATE__{SECTION}__{SUBSECTION}__{KEY}
+
+    Examples:
+        PYDVTATE__INSTRUMENTS__BACKEND=pyvisa
+        PYDVTATE__PHYSICS__UPDATE_RATE_HZ=50.0
+        PYDVTATE__SIMULATOR__HOST=192.168.1.100
+    """
+    prefix = "PYDVTATE__"
+
+    for env_key, env_value in os.environ.items():
+        if not env_key.startswith(prefix):
+            continue
+
+        # Remove prefix and split into parts
+        key_parts = env_key[len(prefix) :].lower().split("__")
+
+        # Navigate/create nested structure
+        current = config_dict
+        for part in key_parts[:-1]:
+            if part not in current:
+                current[part] = {}
+            current = current[part]
+
+        # Set the final value
+        final_key = key_parts[-1]
+        # Try to parse as YAML to handle types (int, float, bool, etc.)
+        try:
+            current[final_key] = yaml.safe_load(env_value)
+        except yaml.YAMLError:
+            # If parsing fails, use as string
+            current[final_key] = env_value
+
+
+def load_config(config_path: str | Path | None = None) -> AppConfig:
+    """Load configuration from YAML file with environment variable overrides.
+
+    Args:
+        config_path: Path to YAML configuration file. If None, uses defaults only.
+
+    Returns:
+        Validated AppConfig instance.
+
+    Raises:
+        FileNotFoundError: If config_path is provided but does not exist.
+        yaml.YAMLError: If YAML file is malformed.
+        pydantic.ValidationError: If configuration is invalid.
+
+    Environment Variables:
+        Configuration can be overridden using environment variables with the
+        pattern PYDVTATE__{SECTION}__{KEY}. For example:
+            PYDVTATE__INSTRUMENTS__BACKEND=pyvisa
+            PYDVTATE__PHYSICS__UPDATE_RATE_HZ=50.0
+    """
+    # Start with empty dict (will use Pydantic defaults)
+    config_dict: dict[str, Any] = {}
+
+    # Load from YAML file if provided
+    if config_path is not None:
+        path = Path(config_path)
+        if not path.exists():
+            raise FileNotFoundError(f"Configuration file not found: {config_path}")
+
+        with path.open("r") as f:
+            loaded = yaml.safe_load(f)
+            if loaded is not None:
+                config_dict = loaded
+
+    # Apply environment variable overrides
+    _apply_env_overrides(config_dict)
+
+    # Validate and return
+    return AppConfig(**config_dict)

src/py_dvt_ate/app/dashboard/app.py

@@ -4,6 +4,7 @@ This module provides an interactive dashboard for visualising the physics
 engine directly, demonstrating thermal-electrical coupling in real-time.
 """
 
+import time
 from collections import deque
 from dataclasses import dataclass, field
 
@@ -11,7 +12,6 @@ import streamlit as st
 
 from py_dvt_ate.simulation.physics.engine import PhysicsEngine
 
-
 # History buffer size for charts
 HISTORY_SIZE = 500
 
@@ -44,12 +44,29 @@ def init_session_state() -> None:
         st.session_state.history = SimulationHistory()
     if "running" not in st.session_state:
         st.session_state.running = False
+    if "last_update" not in st.session_state:
+        st.session_state.last_update = time.time()
+    # Note: time_multiplier, temp_setpoint, input_voltage, output_enabled,
+    # load_current are managed by their respective widgets via keys
 
 
-def step_simulation(steps: int = 10) -> None:
+def step_simulation() -> None:
-    """Advance the simulation by the given number of steps."""
+    """Advance the simulation based on elapsed real time and multiplier."""
     engine: PhysicsEngine = st.session_state.engine
     history: SimulationHistory = st.session_state.history
+    multiplier: float = st.session_state.get("time_multiplier", 10)
+
+    # Calculate how much simulation time to advance
+    current_time = time.time()
+    elapsed_real = current_time - st.session_state.last_update
+    st.session_state.last_update = current_time
+
+    # Simulation time to advance (capped to prevent huge jumps)
+    sim_time_to_advance = min(elapsed_real * multiplier, 2.0)
+
+    # Calculate number of steps needed
+    steps = int(sim_time_to_advance / engine.dt)
+    steps = max(1, min(steps, 1000))  # Clamp between 1 and 1000 steps
 
     for _ in range(steps):
         engine.step()
@@ -66,105 +83,127 @@ def step_simulation(steps: int = 10) -> None:
     history.power_dissipation.append(electrical.power_dissipation)
 
 
-def display_thermal_chart() -> None:
+def sync_engine_from_session_state() -> None:
-    """Display temperature chart."""
+    """Sync engine parameters from session state (called by fragment)."""
-    history: SimulationHistory = st.session_state.history
+    engine: PhysicsEngine = st.session_state.engine
+    engine.set_chamber_setpoint(st.session_state.get("temp_setpoint", 25.0))
+    engine.set_input_voltage(st.session_state.get("input_voltage", 5.0))
+    engine.set_output_enabled(st.session_state.get("output_enabled", False))
+    engine.set_load_current(st.session_state.get("load_current", 100.0) / 1000.0)
 
-    if len(history.time) < 2:
-        st.info("Start the simulation to see temperature data")
-        return
 
-    chart_data = {
+def display_controls() -> None:
-        "Time (s)": list(history.time),
+    """Display simulation control panel in sidebar."""
-        "Chamber": list(history.chamber_temp),
+    st.sidebar.header("Simulation Controls")
-        "Case": list(history.case_temp),
-        "Junction": list(history.junction_temp),
-    }
 
-    st.line_chart(
+    # Start/Stop button
-        chart_data,
+    if st.session_state.running:
-        x="Time (s)",
+        if st.sidebar.button(
-        y=["Chamber", "Case", "Junction"],
+            "Stop Simulation", type="primary", use_container_width=True
-        color=["#1f77b4", "#ff7f0e", "#d62728"],
+        ):
+            st.session_state.running = False
+    else:
+        if st.sidebar.button(
+            "Start Simulation", type="primary", use_container_width=True
+        ):
+            st.session_state.running = True
+            st.session_state.last_update = time.time()
+
+    # Reset button
+    if st.sidebar.button("Reset", use_container_width=True):
+        st.session_state.engine = PhysicsEngine(update_rate_hz=100.0)
+        st.session_state.history = SimulationHistory()
+        st.session_state.running = False
+        st.session_state.last_update = time.time()
+
+    st.sidebar.divider()
+
+    # Time multiplier
+    st.sidebar.subheader("Simulation Speed")
+    st.sidebar.select_slider(
+        "Time Multiplier",
+        options=[1, 2, 5, 10, 20, 50, 100],
+        value=10,
+        format_func=lambda x: f"{x}x",
+        key="time_multiplier",
+    )
+    st.sidebar.caption(
+        f"1 real second = {st.session_state.get('time_multiplier', 10)} simulation seconds"
+    )
+
+    st.sidebar.divider()
+
+    # Temperature setpoint
+    st.sidebar.subheader("Thermal Chamber")
+    st.sidebar.slider(
+        "Temperature Setpoint (C)",
+        min_value=-40.0,
+        max_value=125.0,
+        value=25.0,
+        step=5.0,
+        key="temp_setpoint",
+    )
+
+    st.sidebar.divider()
+
+    # Power supply controls
+    st.sidebar.subheader("Power Supply")
+    st.sidebar.slider(
+        "Input Voltage (V)",
+        min_value=0.0,
+        max_value=12.0,
+        value=5.0,
+        step=0.1,
+        key="input_voltage",
+    )
+
+    st.sidebar.toggle(
+        "Output Enabled",
+        value=False,
+        key="output_enabled",
+    )
+
+    st.sidebar.divider()
+
+    # Load controls
+    st.sidebar.subheader("Electronic Load")
+    st.sidebar.slider(
+        "Load Current (mA)",
+        min_value=0.0,
+        max_value=500.0,
+        value=100.0,
+        step=10.0,
+        key="load_current",
     )
 
 
-def display_self_heating_panel() -> None:
+@st.fragment(run_every=0.1)
-    """Display self-heating demonstration panel."""
+def simulation_display() -> None:
+    """Fragment that displays and updates simulation state."""
     engine: PhysicsEngine = st.session_state.engine
     history: SimulationHistory = st.session_state.history
 
+    # Sync engine parameters from UI controls
+    sync_engine_from_session_state()
+
+    # Step simulation if running
+    if st.session_state.running:
+        step_simulation()
+
+    # Get current state
     thermal = engine.get_thermal_state()
     electrical = engine.get_electrical_state()
 
-    # Calculate temperature rises
+    # Current state metrics
-    delta_t_jc = thermal.junction_temperature - thermal.case_temperature
+    st.subheader("Current State")
-    delta_t_ca = thermal.case_temperature - thermal.chamber_temperature
-
-    col1, col2 = st.columns(2)
-
-    with col1:
-        st.markdown("#### Self-Heating Analysis")
-
-        # Display thermal resistance info
-        st.markdown(
-            f"""
-            | Parameter | Value |
-            |-----------|-------|
-            | Junction-Case Rise (ΔT_jc) | **{delta_t_jc:.2f} °C** |
-            | Case-Ambient Rise (ΔT_ca) | **{delta_t_ca:.2f} °C** |
-            | Power Dissipation | {electrical.power_dissipation * 1000:.1f} mW |
-            | θ_jc (junction-case) | 15 °C/W |
-            | θ_ca (case-ambient) | 5 °C/W |
-            """
-        )
-
-        st.markdown(
-            """
-            **Thermal Coupling:** The junction temperature rises above the case
-            temperature due to power dissipation. This is governed by:
-
-            `T_junction = T_case + P_diss × θ_jc`
-
-            Try increasing the load current or input voltage to see
-            self-heating effects!
-            """
-        )
-
-    with col2:
-        st.markdown("#### Power Dissipation")
-
-        if len(history.time) < 2:
-            st.info("Start the simulation to see power data")
-            return
-
-        power_data = {
-            "Time (s)": list(history.time),
-            "Power (mW)": [p * 1000 for p in history.power_dissipation],
-        }
-
-        st.line_chart(
-            power_data,
-            x="Time (s)",
-            y="Power (mW)",
-            color="#2ca02c",
-        )
-
-
-def display_current_state() -> None:
-    """Display current simulation state metrics."""
-    engine: PhysicsEngine = st.session_state.engine
-    thermal = engine.get_thermal_state()
-    electrical = engine.get_electrical_state()
-
     col1, col2, col3, col4 = st.columns(4)
 
     with col1:
-        st.metric("Chamber Temp", f"{thermal.chamber_temperature:.2f} °C")
+        st.metric("Chamber Temp", f"{thermal.chamber_temperature:.2f} C")
     with col2:
-        st.metric("Case Temp", f"{thermal.case_temperature:.2f} °C")
+        st.metric("Case Temp", f"{thermal.case_temperature:.2f} C")
     with col3:
-        st.metric("Junction Temp", f"{thermal.junction_temperature:.2f} °C")
+        st.metric("Junction Temp", f"{thermal.junction_temperature:.2f} C")
     with col4:
         st.metric("Output Voltage", f"{electrical.output_voltage:.4f} V")
 
@@ -177,82 +216,79 @@ def display_current_state() -> None:
     with col7:
         st.metric("Power Diss.", f"{electrical.power_dissipation * 1000:.2f} mW")
     with col8:
-        st.metric("Sim Time", f"{engine.simulation_time:.2f} s")
+        status = "Running" if st.session_state.running else "Stopped"
+        st.metric(
+            "Sim Time",
+            f"{engine.simulation_time:.1f} s",
+            delta=f"{status} @ {st.session_state.get('time_multiplier', 10):.0f}x",
+        )
 
-
+    # Temperature chart
-def display_controls() -> None:
+    st.subheader("Temperature History")
-    """Display simulation control panel in sidebar."""
+    if len(history.time) < 2:
-    engine: PhysicsEngine = st.session_state.engine
+        st.info("Start the simulation to see temperature data")
-
-    st.sidebar.header("Simulation Controls")
-
-    # Start/Stop button
-    if st.session_state.running:
-        if st.sidebar.button("Stop Simulation", type="primary", use_container_width=True):
-            st.session_state.running = False
-            st.rerun()
     else:
-        if st.sidebar.button(
+        chart_data = {
-            "Start Simulation", type="primary", use_container_width=True
+            "Time (s)": list(history.time),
-        ):
+            "Chamber": list(history.chamber_temp),
-            st.session_state.running = True
+            "Case": list(history.case_temp),
-            st.rerun()
+            "Junction": list(history.junction_temp),
+        }
+        st.line_chart(
+            chart_data,
+            x="Time (s)",
+            y=["Chamber", "Case", "Junction"],
+            color=["#1f77b4", "#ff7f0e", "#d62728"],
+        )
 
-    # Reset button
+    # Self-heating demonstration
-    if st.sidebar.button("Reset", use_container_width=True):
+    st.subheader("Self-Heating Demonstration")
-        st.session_state.engine = PhysicsEngine(update_rate_hz=100.0)
-        st.session_state.history = SimulationHistory()
-        st.session_state.running = False
-        st.rerun()
 
-    st.sidebar.divider()
+    delta_t_jc = thermal.junction_temperature - thermal.case_temperature
+    delta_t_ca = thermal.case_temperature - thermal.chamber_temperature
 
-    # Temperature setpoint
+    col1, col2 = st.columns(2)
-    st.sidebar.subheader("Thermal Chamber")
-    temp_setpoint = st.sidebar.slider(
-        "Temperature Setpoint (°C)",
-        min_value=-40.0,
-        max_value=125.0,
-        value=25.0,
-        step=5.0,
-        key="temp_setpoint",
-    )
-    engine.set_chamber_setpoint(temp_setpoint)
 
-    st.sidebar.divider()
+    with col1:
+        st.markdown("#### Self-Heating Analysis")
+        st.markdown(
+            f"""
+| Parameter | Value |
+|-----------|-------|
+| Junction-Case Rise (dT_jc) | **{delta_t_jc:.2f} C** |
+| Case-Ambient Rise (dT_ca) | **{delta_t_ca:.2f} C** |
+| Power Dissipation | {electrical.power_dissipation * 1000:.1f} mW |
+| theta_jc (junction-case) | 15 C/W |
+| theta_ca (case-ambient) | 5 C/W |
+"""
+        )
+        st.markdown(
+            """
+**Thermal Coupling:** The junction temperature rises above the case
+temperature due to power dissipation. This is governed by:
 
-    # Power supply controls
+`T_junction = T_case + P_diss x theta_jc`
-    st.sidebar.subheader("Power Supply")
-    input_voltage = st.sidebar.slider(
-        "Input Voltage (V)",
-        min_value=0.0,
-        max_value=12.0,
-        value=5.0,
-        step=0.1,
-        key="input_voltage",
-    )
-    engine.set_input_voltage(input_voltage)
 
-    output_enabled = st.sidebar.toggle(
+Try increasing the load current or input voltage to see
-        "Output Enabled",
+self-heating effects!
-        value=engine.is_output_enabled,
+"""
-        key="output_enabled",
+        )
-    )
-    engine.set_output_enabled(output_enabled)
 
-    st.sidebar.divider()
+    with col2:
-
+        st.markdown("#### Power Dissipation")
-    # Load controls
+        if len(history.time) < 2:
-    st.sidebar.subheader("Electronic Load")
+            st.info("Start the simulation to see power data")
-    load_current_ma = st.sidebar.slider(
+        else:
-        "Load Current (mA)",
+            power_data = {
-        min_value=0.0,
+                "Time (s)": list(history.time),
-        max_value=500.0,
+                "Power (mW)": [p * 1000 for p in history.power_dissipation],
-        value=100.0,
+            }
-        step=10.0,
+            st.line_chart(
-        key="load_current",
+                power_data,
-    )
+                x="Time (s)",
-    engine.set_load_current(load_current_ma / 1000.0)
+                y="Power (mW)",
+                color="#2ca02c",
+            )
 
 
 def main() -> None:
@@ -273,25 +309,11 @@ def main() -> None:
 
     init_session_state()
 
-    # Sidebar controls
+    # Sidebar controls (static - doesn't need fragment)
     display_controls()
 
-    # Current state display
+    # Dynamic simulation display (uses fragment for smooth updates)
-    st.subheader("Current State")
+    simulation_display()
-    display_current_state()
-
-    # Temperature chart
-    st.subheader("Temperature History")
-    display_thermal_chart()
-
-    # Self-heating demonstration
-    st.subheader("Self-Heating Demonstration")
-    display_self_heating_panel()
-
-    # Auto-refresh when running
-    if st.session_state.running:
-        step_simulation(steps=10)
-        st.rerun()
 
 
 if __name__ == "__main__":

src/py_dvt_ate/data/__init__.py

@@ -0,0 +1,14 @@
+"""Data persistence layer.
+
+Provides storage for test runs, results, and measurements using
+SQLite for metadata and Parquet for time-series data.
+"""
+
+from py_dvt_ate.data.models import Measurement, TestResult, TestRun, TestStatus
+
+__all__ = [
+    "Measurement",
+    "TestResult",
+    "TestRun",
+    "TestStatus",
+]

src/py_dvt_ate/data/models.py

@@ -0,0 +1,83 @@
+"""Data models for test persistence.
+
+This module defines dataclasses representing test runs, results, and measurements.
+These models map to SQLite tables (for metadata) and Parquet files (for time-series).
+"""
+
+from dataclasses import dataclass, field
+from datetime import datetime
+from enum import Enum
+
+
+class TestStatus(Enum):
+    """Test run status."""
+
+    PENDING = "pending"
+    RUNNING = "running"
+    PASSED = "passed"
+    FAILED = "failed"
+    ERROR = "error"
+    SKIPPED = "skipped"
+
+
+@dataclass
+class TestRun:
+    """Test run metadata.
+
+    Maps to the test_runs SQLite table.
+    """
+
+    id: str  # UUID
+    test_name: str
+    started_at: datetime
+    status: TestStatus
+    config_json: str  # JSON string of test configuration
+    description: str | None = None
+    completed_at: datetime | None = None
+    operator: str | None = None
+    notes: str | None = None
+    created_at: datetime = field(default_factory=datetime.now)
+
+
+@dataclass(frozen=True)
+class TestResult:
+    """Immutable test result with limits.
+
+    Maps to the test_results SQLite table.
+    Represents a single scalar measurement with pass/fail limits.
+    """
+
+    id: str  # UUID
+    test_run_id: str  # Foreign key to test_runs.id
+    parameter: str
+    value: float
+    unit: str
+    measured_at: datetime
+    lower_limit: float | None = None
+    upper_limit: float | None = None
+
+    @property
+    def passed(self) -> bool | None:
+        """Evaluate pass/fail. None if no limits defined."""
+        if self.lower_limit is None and self.upper_limit is None:
+            return None
+        lower_ok = self.lower_limit is None or self.value >= self.lower_limit
+        upper_ok = self.upper_limit is None or self.value <= self.upper_limit
+        return lower_ok and upper_ok
+
+
+@dataclass(frozen=True)
+class Measurement:
+    """Immutable measurement record for time-series data.
+
+    Maps to Parquet files for efficient storage and analysis.
+    Includes measurement conditions (temperature, voltage, current) at time of measurement.
+    """
+
+    timestamp: float  # Seconds since epoch (high precision)
+    parameter: str
+    value: float
+    unit: str
+    temperature: float = 0.0  # Chamber temperature at measurement
+    input_voltage: float = 0.0  # DUT input voltage at measurement
+    load_current: float = 0.0  # DUT load current at measurement

src/py_dvt_ate/data/repository.py

@@ -0,0 +1,359 @@
+"""Data repository implementation using SQLite and Parquet.
+
+This module provides SQLite-based storage for test run metadata and results.
+Time-series measurements are stored separately in Parquet files.
+"""
+
+import json
+import sqlite3
+from abc import ABC, abstractmethod
+from datetime import datetime
+from pathlib import Path
+from typing import Any
+from uuid import UUID, uuid4
+
+import pandas as pd
+
+from py_dvt_ate.data.models import Measurement, TestResult, TestRun, TestStatus
+
+
+class ITestRepository(ABC):
+    """Repository interface for test data."""
+
+    @abstractmethod
+    def create_run(
+        self,
+        test_name: str,
+        config: dict[str, Any],
+        operator: str | None = None,
+        description: str | None = None,
+    ) -> UUID:
+        """Create a new test run and return its ID."""
+
+    @abstractmethod
+    def update_run_status(self, run_id: UUID, status: TestStatus) -> None:
+        """Update the status of a test run."""
+
+    @abstractmethod
+    def complete_run(self, run_id: UUID, status: TestStatus) -> None:
+        """Mark a test run as complete with final status."""
+
+    @abstractmethod
+    def save_result(
+        self,
+        run_id: UUID,
+        parameter: str,
+        value: float,
+        unit: str,
+        lower_limit: float | None = None,
+        upper_limit: float | None = None,
+    ) -> None:
+        """Save a scalar test result."""
+
+    @abstractmethod
+    def save_measurements(
+        self,
+        run_id: UUID,
+        measurements: list[Measurement],
+    ) -> None:
+        """Save time-series measurements (implemented in Parquet extension)."""
+
+    @abstractmethod
+    def get_run(self, run_id: UUID) -> TestRun:
+        """Retrieve test run metadata by ID."""
+
+    @abstractmethod
+    def get_results(self, run_id: UUID) -> list[TestResult]:
+        """Retrieve all test results for a run."""
+
+    @abstractmethod
+    def get_measurements_dataframe(self, run_id: UUID) -> pd.DataFrame | None:
+        """Retrieve measurements as pandas DataFrame."""
+
+
+class SQLiteRepository(ITestRepository):
+    """SQLite-based repository for test data.
+
+    Stores test run metadata and scalar results in SQLite.
+    Time-series measurements are stored in Parquet files.
+    """
+
+    def __init__(self, db_path: str | Path, measurements_dir: str | Path | None = None):
+        """Initialise repository with database and measurements paths.
+
+        Args:
+            db_path: Path to SQLite database file
+            measurements_dir: Directory for Parquet measurement files
+                            (defaults to db_path parent / "measurements")
+        """
+        self.db_path = Path(db_path)
+        self.db_path.parent.mkdir(parents=True, exist_ok=True)
+
+        if measurements_dir is None:
+            self.measurements_dir = self.db_path.parent / "measurements"
+        else:
+            self.measurements_dir = Path(measurements_dir)
+
+        self.measurements_dir.mkdir(parents=True, exist_ok=True)
+        self._init_database()
+
+    def _init_database(self) -> None:
+        """Create database tables if they don't exist."""
+        with sqlite3.connect(self.db_path) as conn:
+            conn.execute(
+                """
+                CREATE TABLE IF NOT EXISTS test_runs (
+                    id TEXT PRIMARY KEY,
+                    test_name TEXT NOT NULL,
+                    description TEXT,
+                    started_at TEXT NOT NULL,
+                    completed_at TEXT,
+                    status TEXT NOT NULL DEFAULT 'pending',
+                    config_json TEXT NOT NULL,
+                    operator TEXT,
+                    notes TEXT,
+                    created_at TEXT NOT NULL DEFAULT (datetime('now'))
+                )
+                """
+            )
+            conn.execute(
+                """
+                CREATE TABLE IF NOT EXISTS test_results (
+                    id TEXT PRIMARY KEY,
+                    test_run_id TEXT NOT NULL,
+                    parameter TEXT NOT NULL,
+                    value REAL NOT NULL,
+                    unit TEXT,
+                    lower_limit REAL,
+                    upper_limit REAL,
+                    passed INTEGER NOT NULL,
+                    measured_at TEXT NOT NULL,
+                    FOREIGN KEY (test_run_id) REFERENCES test_runs(id)
+                )
+                """
+            )
+            conn.execute(
+                "CREATE INDEX IF NOT EXISTS idx_test_runs_status ON test_runs(status)"
+            )
+            conn.execute(
+                "CREATE INDEX IF NOT EXISTS idx_test_runs_name ON test_runs(test_name)"
+            )
+            conn.execute(
+                "CREATE INDEX IF NOT EXISTS idx_test_results_run ON test_results(test_run_id)"
+            )
+            conn.execute(
+                "CREATE INDEX IF NOT EXISTS idx_test_results_param ON test_results(parameter)"
+            )
+            conn.commit()
+
+    def create_run(
+        self,
+        test_name: str,
+        config: dict[str, Any],
+        operator: str | None = None,
+        description: str | None = None,
+    ) -> UUID:
+        """Create a new test run and return its ID."""
+        run_id = uuid4()
+        started_at = datetime.now()
+        config_json = json.dumps(config)
+
+        with sqlite3.connect(self.db_path) as conn:
+            conn.execute(
+                """
+                INSERT INTO test_runs (
+                    id, test_name, description, started_at, status,
+                    config_json, operator, created_at
+                )
+                VALUES (?, ?, ?, ?, ?, ?, ?, ?)
+                """,
+                (
+                    str(run_id),
+                    test_name,
+                    description,
+                    started_at.isoformat(),
+                    TestStatus.PENDING.value,
+                    config_json,
+                    operator,
+                    datetime.now().isoformat(),
+                ),
+            )
+            conn.commit()
+
+        return run_id
+
+    def update_run_status(self, run_id: UUID, status: TestStatus) -> None:
+        """Update the status of a test run."""
+        with sqlite3.connect(self.db_path) as conn:
+            conn.execute(
+                "UPDATE test_runs SET status = ? WHERE id = ?",
+                (status.value, str(run_id)),
+            )
+            conn.commit()
+
+    def complete_run(self, run_id: UUID, status: TestStatus) -> None:
+        """Mark a test run as complete with final status."""
+        completed_at = datetime.now()
+
+        with sqlite3.connect(self.db_path) as conn:
+            conn.execute(
+                """
+                UPDATE test_runs
+                SET status = ?, completed_at = ?
+                WHERE id = ?
+                """,
+                (status.value, completed_at.isoformat(), str(run_id)),
+            )
+            conn.commit()
+
+    def save_result(
+        self,
+        run_id: UUID,
+        parameter: str,
+        value: float,
+        unit: str,
+        lower_limit: float | None = None,
+        upper_limit: float | None = None,
+    ) -> None:
+        """Save a scalar test result."""
+        result_id = uuid4()
+        measured_at = datetime.now()
+
+        # Calculate pass/fail
+        passed = 1  # Default to pass if no limits
+        if lower_limit is not None or upper_limit is not None:
+            lower_ok = lower_limit is None or value >= lower_limit
+            upper_ok = upper_limit is None or value <= upper_limit
+            passed = 1 if (lower_ok and upper_ok) else 0
+
+        with sqlite3.connect(self.db_path) as conn:
+            conn.execute(
+                """
+                INSERT INTO test_results (
+                    id, test_run_id, parameter, value, unit,
+                    lower_limit, upper_limit, passed, measured_at
+                )
+                VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)
+                """,
+                (
+                    str(result_id),
+                    str(run_id),
+                    parameter,
+                    value,
+                    unit,
+                    lower_limit,
+                    upper_limit,
+                    passed,
+                    measured_at.isoformat(),
+                ),
+            )
+            conn.commit()
+
+    def save_measurements(
+        self,
+        run_id: UUID,
+        measurements: list[Measurement],
+    ) -> None:
+        """Save time-series measurements to Parquet file.
+
+        Measurements are stored in Parquet format for efficient time-series storage.
+        File path: {measurements_dir}/run_{run_id}/measurements.parquet
+        """
+        if not measurements:
+            return
+
+        # Create run-specific directory
+        run_dir = self.measurements_dir / f"run_{run_id}"
+        run_dir.mkdir(parents=True, exist_ok=True)
+
+        # Convert measurements to DataFrame
+        data = {
+            "timestamp": [m.timestamp for m in measurements],
+            "parameter": [m.parameter for m in measurements],
+            "value": [m.value for m in measurements],
+            "unit": [m.unit for m in measurements],
+            "temperature": [m.temperature for m in measurements],
+            "input_voltage": [m.input_voltage for m in measurements],
+            "load_current": [m.load_current for m in measurements],
+        }
+        df = pd.DataFrame(data)
+
+        # Save to Parquet (append mode if file exists)
+        parquet_path = run_dir / "measurements.parquet"
+        if parquet_path.exists():
+            # Read existing data and append
+            existing_df = pd.read_parquet(parquet_path)
+            df = pd.concat([existing_df, df], ignore_index=True)
+
+        df.to_parquet(parquet_path, index=False, engine="pyarrow")
+
+    def get_run(self, run_id: UUID) -> TestRun:
+        """Retrieve test run metadata by ID."""
+        with sqlite3.connect(self.db_path) as conn:
+            conn.row_factory = sqlite3.Row
+            cursor = conn.execute(
+                "SELECT * FROM test_runs WHERE id = ?",
+                (str(run_id),),
+            )
+            row = cursor.fetchone()
+
+            if row is None:
+                msg = f"Test run {run_id} not found"
+                raise ValueError(msg)
+
+            return TestRun(
+                id=row["id"],
+                test_name=row["test_name"],
+                description=row["description"],
+                started_at=datetime.fromisoformat(row["started_at"]),
+                completed_at=(
+                    datetime.fromisoformat(row["completed_at"])
+                    if row["completed_at"]
+                    else None
+                ),
+                status=TestStatus(row["status"]),
+                config_json=row["config_json"],
+                operator=row["operator"],
+                notes=row["notes"],
+                created_at=datetime.fromisoformat(row["created_at"]),
+            )
+
+    def get_results(self, run_id: UUID) -> list[TestResult]:
+        """Retrieve all test results for a run."""
+        with sqlite3.connect(self.db_path) as conn:
+            conn.row_factory = sqlite3.Row
+            cursor = conn.execute(
+                "SELECT * FROM test_results WHERE test_run_id = ?",
+                (str(run_id),),
+            )
+            rows = cursor.fetchall()
+
+            return [
+                TestResult(
+                    id=row["id"],
+                    test_run_id=row["test_run_id"],
+                    parameter=row["parameter"],
+                    value=row["value"],
+                    unit=row["unit"],
+                    lower_limit=row["lower_limit"],
+                    upper_limit=row["upper_limit"],
+                    measured_at=datetime.fromisoformat(row["measured_at"]),
+                )
+                for row in rows
+            ]
+
+    def get_measurements_dataframe(self, run_id: UUID) -> pd.DataFrame | None:
+        """Retrieve measurements as pandas DataFrame from Parquet file.
+
+        Args:
+            run_id: Test run ID
+
+        Returns:
+            DataFrame with measurement data, or None if no measurements exist
+        """
+        parquet_path = self.measurements_dir / f"run_{run_id}" / "measurements.parquet"
+
+        if not parquet_path.exists():
+            return None
+
+        return pd.read_parquet(parquet_path)

src/py_dvt_ate/framework/__init__.py

@@ -3,3 +3,20 @@
 Provides test sequencing, measurement logging, limit checking,
 and runtime context management for DVT characterisation tests.
 """
+
+from py_dvt_ate.framework.context import ITest, TestContext
+from py_dvt_ate.framework.limits import Limit, LimitSet, check_value, evaluate_results
+from py_dvt_ate.framework.logger import ITestLogger, TestLogger
+from py_dvt_ate.framework.runner import TestRunner
+
+__all__ = [
+    "ITest",
+    "ITestLogger",
+    "Limit",
+    "LimitSet",
+    "TestContext",
+    "TestLogger",
+    "TestRunner",
+    "check_value",
+    "evaluate_results",
+]

src/py_dvt_ate/framework/context.py

@@ -0,0 +1,111 @@
+"""Test framework context and interface definitions.
+
+This module defines the core abstractions for the test executive framework:
+- TestContext: Runtime context passed to tests during execution
+- ITest: Abstract base class that all DVT tests must implement
+
+The test framework orchestrates test execution, measurement logging, and
+result evaluation against limits.
+"""
+
+from abc import ABC, abstractmethod
+from dataclasses import dataclass
+from typing import TYPE_CHECKING, Any
+from uuid import UUID
+
+from py_dvt_ate.data.models import TestStatus
+
+if TYPE_CHECKING:
+    # Avoid circular imports while maintaining type checking
+    from py_dvt_ate.framework.logger import ITestLogger
+    from py_dvt_ate.instruments.factory import InstrumentSet
+
+
+@dataclass
+class TestContext:
+    """Runtime context for test execution.
+
+    Provides access to instruments, logging, and configuration during test
+    execution. Passed to each test's execute() method.
+
+    Attributes:
+        run_id: Unique identifier for this test run (UUID).
+        instruments: Hardware abstraction layer providing access to all instruments.
+        logger: Test logger for recording measurements and events.
+        config: Test-specific configuration dictionary.
+    """
+
+    run_id: UUID
+    instruments: "InstrumentSet"
+    logger: "ITestLogger"
+    config: dict[str, Any]
+
+
+class ITest(ABC):
+    """Abstract base class for DVT test implementations.
+
+    All characterisation tests must inherit from this class and implement
+    the required properties and methods. The test runner uses these to
+    discover, describe, and execute tests.
+
+    Example:
+        class TempCoTest(ITest):
+            @property
+            def name(self) -> str:
+                return "tempco"
+
+            @property
+            def description(self) -> str:
+                return "Output voltage temperature coefficient"
+
+            def execute(self, context: TestContext) -> TestStatus:
+                # Test implementation...
+                return TestStatus.PASSED
+    """
+
+    @property
+    @abstractmethod
+    def name(self) -> str:
+        """Return the unique test identifier.
+
+        Used for test discovery and selection. Should be lowercase,
+        alphanumeric with underscores (e.g., "tempco", "load_regulation").
+
+        Returns:
+            Unique test name string.
+        """
+        pass
+
+    @property
+    @abstractmethod
+    def description(self) -> str:
+        """Return a human-readable test description.
+
+        Describes what the test measures or characterises. Displayed in
+        reports and user interfaces.
+
+        Returns:
+            Brief description of the test purpose.
+        """
+        pass
+
+    @abstractmethod
+    def execute(self, context: TestContext) -> TestStatus:
+        """Execute the test with the given context.
+
+        Contains the test logic: configure instruments, take measurements,
+        log results, and evaluate pass/fail. The test should use the
+        context.logger to record measurements and context.instruments to
+        control equipment.
+
+        Args:
+            context: Runtime context with instruments, logger, and config.
+
+        Returns:
+            Final test status (PASSED, FAILED, ERROR, etc.).
+
+        Raises:
+            Exception: If a critical error occurs during test execution.
+                      The test runner will catch this and mark the test as ERROR.
+        """
+        pass

src/py_dvt_ate/framework/limits.py

@@ -0,0 +1,238 @@
+"""Limit checking utilities for test result evaluation.
+
+This module provides utilities for evaluating measurements against specification
+limits and determining pass/fail status. Used by tests to check if results meet
+requirements and by the test runner to determine overall test status.
+"""
+
+from dataclasses import dataclass
+from typing import Any
+
+from py_dvt_ate.data.models import TestResult, TestStatus
+
+
+@dataclass(frozen=True)
+class Limit:
+    """Specification limit for a parameter.
+
+    Represents a single limit specification with optional lower and upper bounds.
+    Used to define test specifications and evaluate pass/fail.
+
+    Attributes:
+        parameter: Parameter name this limit applies to.
+        lower: Optional lower limit (inclusive). None means no lower limit.
+        upper: Optional upper limit (inclusive). None means no upper limit.
+        unit: Unit of measurement for the limits.
+
+    Example:
+        temp_co_limit = Limit("temp_co", lower=-50.0, upper=50.0, unit="ppm/°C")
+    """
+
+    parameter: str
+    lower: float | None = None
+    upper: float | None = None
+    unit: str = ""
+
+    def check(self, value: float) -> bool | None:
+        """Check if a value is within this limit.
+
+        Args:
+            value: Value to check against limits.
+
+        Returns:
+            True if value is within limits, False if outside limits.
+            None if no limits are defined (informational parameter).
+
+        Example:
+            limit = Limit("v_out", lower=3.25, upper=3.35, unit="V")
+            limit.check(3.30)  # Returns True
+            limit.check(3.40)  # Returns False
+        """
+        if self.lower is None and self.upper is None:
+            return None
+
+        lower_ok = self.lower is None or value >= self.lower
+        upper_ok = self.upper is None or value <= self.upper
+        return lower_ok and upper_ok
+
+
+@dataclass(frozen=True)
+class LimitSet:
+    """Collection of limits for a test.
+
+    Groups multiple parameter limits together as a test specification.
+    Can be loaded from configuration or defined programmatically.
+
+    Attributes:
+        name: Name of this limit set (e.g., "nominal", "extended").
+        limits: Dictionary mapping parameter names to Limit objects.
+
+    Example:
+        limits = LimitSet(
+            name="nominal",
+            limits={
+                "temp_co": Limit("temp_co", -50.0, 50.0, "ppm/°C"),
+                "v_out": Limit("v_out", 3.25, 3.35, "V"),
+            }
+        )
+    """
+
+    name: str
+    limits: dict[str, Limit]
+
+    def get_limit(self, parameter: str) -> Limit | None:
+        """Get the limit for a specific parameter.
+
+        Args:
+            parameter: Parameter name to look up.
+
+        Returns:
+            Limit object if found, None if parameter has no limit defined.
+        """
+        return self.limits.get(parameter)
+
+    def check(self, parameter: str, value: float) -> bool | None:
+        """Check if a value is within limits for a parameter.
+
+        Args:
+            parameter: Parameter name.
+            value: Value to check.
+
+        Returns:
+            True if within limits, False if outside limits.
+            None if parameter has no limit defined.
+        """
+        limit = self.get_limit(parameter)
+        if limit is None:
+            return None
+        return limit.check(value)
+
+    @classmethod
+    def from_dict(cls, name: str, limits_dict: dict[str, Any]) -> "LimitSet":
+        """Create a LimitSet from a dictionary.
+
+        Useful for loading limit sets from YAML configuration files.
+
+        Args:
+            name: Name for this limit set.
+            limits_dict: Dictionary with parameter names as keys and limit
+                        specifications as values. Each limit spec should have:
+                        - "lower": Optional lower limit
+                        - "upper": Optional upper limit
+                        - "unit": Unit of measurement
+
+        Returns:
+            LimitSet instance.
+
+        Example:
+            config = {
+                "temp_co": {"lower": -50.0, "upper": 50.0, "unit": "ppm/°C"},
+                "v_out": {"lower": 3.25, "upper": 3.35, "unit": "V"},
+            }
+            limits = LimitSet.from_dict("nominal", config)
+        """
+        limits = {}
+        for param, spec in limits_dict.items():
+            limits[param] = Limit(
+                parameter=param,
+                lower=spec.get("lower"),
+                upper=spec.get("upper"),
+                unit=spec.get("unit", ""),
+            )
+        return cls(name=name, limits=limits)
+
+
+def check_value(
+    value: float,
+    lower: float | None = None,
+    upper: float | None = None,
+) -> bool | None:
+    """Check if a value is within specified limits.
+
+    Utility function for quick limit checking without creating Limit objects.
+
+    Args:
+        value: Value to check.
+        lower: Optional lower limit (inclusive).
+        upper: Optional upper limit (inclusive).
+
+    Returns:
+        True if value is within limits, False if outside limits.
+        None if no limits are specified.
+
+    Example:
+        check_value(3.30, lower=3.25, upper=3.35)  # Returns True
+        check_value(3.40, lower=3.25, upper=3.35)  # Returns False
+        check_value(3.30)  # Returns None (no limits)
+    """
+    if lower is None and upper is None:
+        return None
+
+    lower_ok = lower is None or value >= lower
+    upper_ok = upper is None or value <= upper
+    return lower_ok and upper_ok
+
+
+def evaluate_results(results: list[TestResult]) -> TestStatus:
+    """Evaluate a list of test results to determine overall status.
+
+    Aggregates multiple test results into a single pass/fail determination.
+    If any result fails its limits, the overall status is FAILED.
+    If all results pass (or have no limits), the overall status is PASSED.
+
+    Args:
+        results: List of TestResult objects to evaluate.
+
+    Returns:
+        TestStatus.PASSED if all results pass their limits.
+        TestStatus.FAILED if any result fails its limits.
+        TestStatus.PASSED if no results have limits defined (informational only).
+
+    Example:
+        results = [
+            TestResult(..., value=25.0, lower_limit=-50.0, upper_limit=50.0),
+            TestResult(..., value=3.30, lower_limit=3.25, upper_limit=3.35),
+        ]
+        status = evaluate_results(results)  # Returns TestStatus.PASSED
+    """
+    if not results:
+        return TestStatus.PASSED
+
+    # Check if any result failed
+    for result in results:
+        if result.passed is False:
+            return TestStatus.FAILED
+
+    # All results passed (or had no limits)
+    return TestStatus.PASSED
+
+
+def format_limit_violation(result: TestResult) -> str:
+    """Format a limit violation message for a failed result.
+
+    Creates a human-readable message describing why a result failed.
+    Useful for logging and reporting.
+
+    Args:
+        result: TestResult that failed its limits.
+
+    Returns:
+        Formatted violation message.
+
+    Example:
+        result = TestResult(..., parameter="v_out", value=3.40,
+                           lower_limit=3.25, upper_limit=3.35, unit="V")
+        message = format_limit_violation(result)
+        # Returns: "v_out: 3.400 V [FAIL] (limits: 3.250 to 3.350 V)"
+    """
+    status = "PASS" if result.passed else "FAIL"
+    limits_str = ""
+
+    if result.lower_limit is not None and result.upper_limit is not None:
+        limits_str = f" (limits: {result.lower_limit:.3f} to {result.upper_limit:.3f} {result.unit})"
+    elif result.lower_limit is not None:
+        limits_str = f" (minimum: {result.lower_limit:.3f} {result.unit})"
+    elif result.upper_limit is not None:
+        limits_str = f" (maximum: {result.upper_limit:.3f} {result.unit})"
+
+    return f"{result.parameter}: {result.value:.3f} {result.unit} [{status}]{limits_str}"

src/py_dvt_ate/framework/logger.py

@@ -0,0 +1,222 @@
+"""Test logger for recording measurements and events.
+
+This module provides the logging infrastructure for DVT tests. The test logger
+records time-series measurements, scalar results with limits, and event messages
+during test execution.
+"""
+
+import time
+from abc import ABC, abstractmethod
+from datetime import datetime
+from uuid import UUID
+
+from py_dvt_ate.data.models import Measurement
+from py_dvt_ate.data.repository import ITestRepository
+
+
+class ITestLogger(ABC):
+    """Abstract interface for test data logging.
+
+    Provides methods for logging measurements, results, and events during
+    test execution. Implementations are responsible for persisting this
+    data to the appropriate storage backend.
+    """
+
+    @abstractmethod
+    def log_measurement(
+        self,
+        parameter: str,
+        value: float,
+        unit: str,
+        conditions: dict[str, float] | None = None,
+    ) -> None:
+        """Log a time-series measurement with environmental conditions.
+
+        Used for logging raw measurements taken during the test. These are
+        stored as time-series data for later analysis and plotting.
+
+        Args:
+            parameter: Measurement parameter name (e.g., "v_out", "i_q").
+            value: Measured value.
+            unit: Unit of measurement (e.g., "V", "A", "°C").
+            conditions: Optional environmental conditions at time of measurement:
+                       - "temperature": Chamber temperature (°C)
+                       - "input_voltage": DUT input voltage (V)
+                       - "load_current": DUT load current (A)
+
+        Example:
+            logger.log_measurement(
+                "v_out", 3.301, "V",
+                conditions={"temperature": 25.0, "input_voltage": 5.0}
+            )
+        """
+        pass
+
+    @abstractmethod
+    def log_result(
+        self,
+        parameter: str,
+        value: float,
+        unit: str,
+        lower_limit: float | None = None,
+        upper_limit: float | None = None,
+    ) -> None:
+        """Log a scalar test result with pass/fail limits.
+
+        Used for logging calculated or derived results that will be evaluated
+        against specification limits. These appear in test reports and determine
+        overall pass/fail status.
+
+        Args:
+            parameter: Result parameter name (e.g., "temp_co", "load_reg").
+            value: Calculated or measured value.
+            unit: Unit of measurement (e.g., "ppm/°C", "%", "mV").
+            lower_limit: Optional lower limit for pass/fail evaluation.
+            upper_limit: Optional upper limit for pass/fail evaluation.
+
+        Example:
+            logger.log_result(
+                "temp_co", 23.5, "ppm/°C",
+                lower_limit=-50.0, upper_limit=50.0
+            )
+        """
+        pass
+
+    @abstractmethod
+    def log_event(self, message: str, level: str = "INFO") -> None:
+        """Log a test event or message.
+
+        Used for logging informational messages, warnings, and errors during
+        test execution. Useful for debugging and understanding test flow.
+
+        Args:
+            message: Event message text.
+            level: Log level ("DEBUG", "INFO", "WARNING", "ERROR").
+
+        Example:
+            logger.log_event("Waiting for thermal stability", level="INFO")
+        """
+        pass
+
+    @abstractmethod
+    def flush(self) -> None:
+        """Flush any buffered data to storage.
+
+        Forces any buffered measurements or results to be written to the
+        underlying storage backend. Called automatically at end of test,
+        but can be called manually for long-running tests.
+        """
+        pass
+
+
+class TestLogger(ITestLogger):
+    """Concrete test logger implementation using repository pattern.
+
+    Buffers measurements in memory and writes them in batches to a
+    repository for efficiency. Results and events are written immediately.
+
+    Attributes:
+        run_id: UUID of the test run this logger is associated with.
+        repository: Data repository for persisting measurements and results.
+        measurement_buffer: In-memory buffer of measurements awaiting write.
+        buffer_size: Number of measurements to buffer before auto-flush.
+    """
+
+    def __init__(
+        self,
+        run_id: UUID,
+        repository: ITestRepository,
+        buffer_size: int = 100,
+    ):
+        """Initialise test logger.
+
+        Args:
+            run_id: UUID of the test run to associate logs with.
+            repository: Repository for persisting data.
+            buffer_size: Number of measurements to buffer before auto-flush.
+                        Default 100 provides good balance of performance
+                        and memory usage.
+        """
+        self.run_id = run_id
+        self.repository = repository
+        self.buffer_size = buffer_size
+        self.measurement_buffer: list[Measurement] = []
+
+    def log_measurement(
+        self,
+        parameter: str,
+        value: float,
+        unit: str,
+        conditions: dict[str, float] | None = None,
+    ) -> None:
+        """Log a time-series measurement with environmental conditions.
+
+        Measurements are buffered in memory and written to the repository
+        in batches for efficiency.
+        """
+        conditions = conditions or {}
+        measurement = Measurement(
+            timestamp=time.time(),
+            parameter=parameter,
+            value=value,
+            unit=unit,
+            temperature=conditions.get("temperature", 0.0),
+            input_voltage=conditions.get("input_voltage", 0.0),
+            load_current=conditions.get("load_current", 0.0),
+        )
+        self.measurement_buffer.append(measurement)
+
+        # Auto-flush when buffer is full
+        if len(self.measurement_buffer) >= self.buffer_size:
+            self.flush()
+
+    def log_result(
+        self,
+        parameter: str,
+        value: float,
+        unit: str,
+        lower_limit: float | None = None,
+        upper_limit: float | None = None,
+    ) -> None:
+        """Log a scalar test result with pass/fail limits.
+
+        Results are written immediately to the repository (not buffered).
+        """
+        self.repository.save_result(
+            run_id=self.run_id,
+            parameter=parameter,
+            value=value,
+            unit=unit,
+            lower_limit=lower_limit,
+            upper_limit=upper_limit,
+        )
+
+    def log_event(self, message: str, level: str = "INFO") -> None:
+        """Log a test event or message.
+
+        Events are currently logged to console. Future versions may
+        persist events to the repository.
+        """
+        timestamp = datetime.now().strftime("%H:%M:%S.%f")[:-3]
+        print(f"[{timestamp}] {level:7s} {message}")
+
+    def flush(self) -> None:
+        """Flush buffered measurements to repository.
+
+        Writes all buffered measurements to the repository in a single
+        batch operation, then clears the buffer.
+        """
+        if self.measurement_buffer:
+            self.repository.save_measurements(
+                run_id=self.run_id,
+                measurements=self.measurement_buffer,
+            )
+            self.measurement_buffer.clear()
+
+    def __del__(self) -> None:
+        """Ensure buffered data is flushed on logger destruction."""
+        try:
+            self.flush()
+        except Exception:
+            # Ignore errors during cleanup
+            pass

src/py_dvt_ate/framework/runner.py

@@ -0,0 +1,203 @@
+"""Test runner for orchestrating DVT test execution.
+
+This module provides the TestRunner class, which coordinates test execution,
+manages test lifecycle, and ensures proper logging and error handling.
+"""
+
+import json
+import traceback
+from typing import Any
+from uuid import UUID
+
+from py_dvt_ate.data.models import TestStatus
+from py_dvt_ate.data.repository import ITestRepository
+from py_dvt_ate.framework.context import ITest, TestContext
+from py_dvt_ate.framework.limits import evaluate_results
+from py_dvt_ate.framework.logger import TestLogger
+from py_dvt_ate.instruments.factory import InstrumentSet
+
+
+class TestRunner:
+    """Orchestrates DVT test execution.
+
+    The test runner manages the complete test lifecycle:
+    1. Creates a test run record in the repository
+    2. Sets up logging and context
+    3. Executes the test with proper error handling
+    4. Evaluates results against limits
+    5. Updates final status and flushes data
+
+    Attributes:
+        repository: Data repository for persisting test results.
+
+    Example:
+        runner = TestRunner(repository)
+        instruments = factory.create(config)
+        run_id = runner.run_test(
+            test=TempCoTest(),
+            instruments=instruments,
+            config={"temp_points": [-40, 25, 85]},
+            operator="alice@example.com"
+        )
+    """
+
+    def __init__(self, repository: ITestRepository):
+        """Initialise test runner.
+
+        Args:
+            repository: Repository for persisting test data.
+        """
+        self.repository = repository
+
+    def run_test(
+        self,
+        test: ITest,
+        instruments: InstrumentSet,
+        config: dict[str, Any] | None = None,
+        operator: str | None = None,
+        description: str | None = None,
+    ) -> UUID:
+        """Run a DVT test with full lifecycle management.
+
+        Creates a test run, executes the test with proper error handling,
+        evaluates results, and updates final status. All measurements and
+        results are persisted to the repository.
+
+        Args:
+            test: Test instance to execute (implements ITest).
+            instruments: Instrument set for test to use.
+            config: Optional test-specific configuration dictionary.
+            operator: Optional operator identifier (e.g., email address).
+            description: Optional human-readable test run description.
+
+        Returns:
+            UUID of the test run. Can be used to retrieve results later.
+
+        Raises:
+            Exception: Only if repository operations fail. Test execution
+                      errors are caught and recorded as ERROR status.
+
+        Example:
+            run_id = runner.run_test(
+                test=TempCoTest(),
+                instruments=instruments,
+                config={"temp_points": [-40, 25, 85]},
+                operator="alice@example.com",
+                description="Characterisation run #42"
+            )
+            print(f"Test run ID: {run_id}")
+        """
+        config = config or {}
+
+        # Create test run record
+        run_id = self.repository.create_run(
+            test_name=test.name,
+            config=config,
+            operator=operator,
+            description=description or test.description,
+        )
+
+        # Create logger for this run
+        logger = TestLogger(run_id=run_id, repository=self.repository)
+
+        # Create test context
+        context = TestContext(
+            run_id=run_id,
+            instruments=instruments,
+            logger=logger,
+            config=config,
+        )
+
+        # Update status to running
+        self.repository.update_run_status(run_id, TestStatus.RUNNING)
+
+        # Execute test with error handling
+        try:
+            logger.log_event(f"Starting test: {test.name}", level="INFO")
+            logger.log_event(f"Description: {test.description}", level="INFO")
+
+            # Log configuration
+            if config:
+                config_str = json.dumps(config, indent=2)
+                logger.log_event(f"Configuration:\n{config_str}", level="DEBUG")
+
+            # Execute the test
+            status = test.execute(context)
+
+            # Flush any buffered measurements
+            logger.flush()
+
+            # Evaluate results if test didn't explicitly set status
+            if status == TestStatus.RUNNING:
+                results = self.repository.get_results(run_id)
+                status = evaluate_results(results)
+                logger.log_event(
+                    f"Test completed. Evaluated {len(results)} results: {status.value}",
+                    level="INFO",
+                )
+
+            # Update final status
+            self.repository.complete_run(run_id, status)
+            logger.log_event(f"Test finished with status: {status.value}", level="INFO")
+
+        except KeyboardInterrupt:
+            # User interrupted - mark as error but don't swallow interrupt
+            logger.log_event("Test interrupted by user", level="WARNING")
+            logger.flush()
+            self.repository.complete_run(run_id, TestStatus.ERROR)
+            raise
+
+        except Exception as e:
+            # Test execution error - log and mark as ERROR
+            error_msg = f"Test execution failed: {e}"
+            logger.log_event(error_msg, level="ERROR")
+            logger.log_event(traceback.format_exc(), level="DEBUG")
+            logger.flush()
+            self.repository.complete_run(run_id, TestStatus.ERROR)
+            logger.log_event("Test finished with status: ERROR", level="INFO")
+
+        return run_id
+
+    def run_tests(
+        self,
+        tests: list[ITest],
+        instruments: InstrumentSet,
+        config: dict[str, Any] | None = None,
+        operator: str | None = None,
+    ) -> list[UUID]:
+        """Run multiple tests sequentially.
+
+        Convenience method for running a suite of tests. Each test is run
+        independently with its own test run record. If one test fails, the
+        remaining tests still execute.
+
+        Args:
+            tests: List of test instances to execute.
+            instruments: Instrument set shared by all tests.
+            config: Optional configuration applied to all tests.
+            operator: Optional operator identifier.
+
+        Returns:
+            List of test run UUIDs in execution order.
+
+        Example:
+            run_ids = runner.run_tests(
+                tests=[TempCoTest(), LoadRegTest(), LineRegTest()],
+                instruments=instruments,
+                config={"common_setting": 42},
+                operator="alice@example.com"
+            )
+            for run_id in run_ids:
+                run = repository.get_run(run_id)
+                print(f"{run.test_name}: {run.status.value}")
+        """
+        run_ids = []
+        for test in tests:
+            run_id = self.run_test(
+                test=test,
+                instruments=instruments,
+                config=config,
+                operator=operator,
+            )
+            run_ids.append(run_id)
+        return run_ids

src/py_dvt_ate/instruments/__init__.py

@@ -7,3 +7,23 @@ This package provides everything needed to communicate with lab instruments:
 - Instrument drivers
 - Factory for creating configured instrument sets
 """
+
+from py_dvt_ate.instruments.factory import (
+    InstrumentConfig,
+    InstrumentFactory,
+    InstrumentSet,
+)
+from py_dvt_ate.instruments.interfaces import (
+    IMultimeter,
+    IPowerSupply,
+    IThermalChamber,
+)
+
+__all__ = [
+    "IThermalChamber",
+    "IPowerSupply",
+    "IMultimeter",
+    "InstrumentSet",
+    "InstrumentConfig",
+    "InstrumentFactory",
+]

src/py_dvt_ate/instruments/drivers/__init__.py

@@ -3,3 +3,15 @@
 Each driver translates high-level operations into SCPI commands
 and handles responses from instruments.
 """
+
+from py_dvt_ate.instruments.drivers.base import BaseDriver
+from py_dvt_ate.instruments.drivers.chamber import ThermalChamberDriver
+from py_dvt_ate.instruments.drivers.multimeter import MultimeterDriver
+from py_dvt_ate.instruments.drivers.power_supply import PowerSupplyDriver
+
+__all__ = [
+    "BaseDriver",
+    "ThermalChamberDriver",
+    "PowerSupplyDriver",
+    "MultimeterDriver",
+]

src/py_dvt_ate/instruments/drivers/base.py

@@ -0,0 +1,197 @@
+"""Base class for SCPI instrument drivers.
+
+This module provides the foundation for implementing client-side instrument
+drivers that communicate via SCPI commands over a transport layer.
+"""
+
+from typing import TYPE_CHECKING
+
+if TYPE_CHECKING:
+    from py_dvt_ate.instruments.transport.base import Transport
+
+
+class BaseDriver:
+    """Base class for SCPI instrument drivers.
+
+    Provides common functionality for communicating with instruments via
+    SCPI commands. Subclasses implement instrument-specific command methods.
+
+    All drivers depend on a Transport instance for low-level communication.
+
+    Attributes:
+        transport: The transport layer for communication.
+    """
+
+    def __init__(self, transport: "Transport") -> None:
+        """Initialise the driver with a transport layer.
+
+        Args:
+            transport: Transport instance for communication (TCP, VISA, etc.).
+        """
+        self.transport = transport
+
+    def connect(self) -> None:
+        """Establish connection to the instrument.
+
+        Raises:
+            ConnectionError: If connection fails.
+        """
+        self.transport.connect()
+
+    def disconnect(self) -> None:
+        """Close connection to the instrument.
+
+        Safe to call multiple times (idempotent).
+        """
+        self.transport.disconnect()
+
+    @property
+    def is_connected(self) -> bool:
+        """Check if connection is active.
+
+        Returns:
+            True if connected, False otherwise.
+        """
+        return self.transport.is_connected
+
+    def write(self, command: str) -> None:
+        """Send a SCPI command to the instrument.
+
+        Args:
+            command: SCPI command string (without terminator).
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If write fails.
+        """
+        self.transport.write(command)
+
+    def query(self, command: str, timeout: float | None = None) -> str:
+        """Send a SCPI query and read the response.
+
+        Args:
+            command: SCPI query string (without terminator).
+            timeout: Read timeout in seconds. None uses default.
+
+        Returns:
+            Response string from instrument.
+
+        Raises:
+            ConnectionError: If not connected.
+            TimeoutError: If read times out.
+            IOError: If communication fails.
+        """
+        return self.transport.query(command, timeout)
+
+    def query_float(self, command: str, timeout: float | None = None) -> float:
+        """Send a SCPI query and parse response as float.
+
+        Args:
+            command: SCPI query string.
+            timeout: Read timeout in seconds.
+
+        Returns:
+            Parsed floating-point value.
+
+        Raises:
+            ConnectionError: If not connected.
+            TimeoutError: If read times out.
+            IOError: If communication fails.
+            ValueError: If response cannot be parsed as float.
+        """
+        response = self.query(command, timeout)
+        try:
+            return float(response.strip())
+        except ValueError as err:
+            raise ValueError(f"Cannot parse '{response}' as float") from err
+
+    def query_int(self, command: str, timeout: float | None = None) -> int:
+        """Send a SCPI query and parse response as integer.
+
+        Args:
+            command: SCPI query string.
+            timeout: Read timeout in seconds.
+
+        Returns:
+            Parsed integer value.
+
+        Raises:
+            ConnectionError: If not connected.
+            TimeoutError: If read times out.
+            IOError: If communication fails.
+            ValueError: If response cannot be parsed as integer.
+        """
+        response = self.query(command, timeout)
+        try:
+            return int(response.strip())
+        except ValueError as err:
+            raise ValueError(f"Cannot parse '{response}' as int") from err
+
+    def query_bool(self, command: str, timeout: float | None = None) -> bool:
+        """Send a SCPI query and parse response as boolean.
+
+        Interprets "1", "ON", "TRUE" as True; "0", "OFF", "FALSE" as False.
+
+        Args:
+            command: SCPI query string.
+            timeout: Read timeout in seconds.
+
+        Returns:
+            Parsed boolean value.
+
+        Raises:
+            ConnectionError: If not connected.
+            TimeoutError: If read times out.
+            IOError: If communication fails.
+            ValueError: If response cannot be parsed as boolean.
+        """
+        response = self.query(command, timeout).strip().upper()
+        if response in ("1", "ON", "TRUE"):
+            return True
+        if response in ("0", "OFF", "FALSE"):
+            return False
+        raise ValueError(f"Cannot parse '{response}' as bool")
+
+    def identify(self) -> str:
+        """Query instrument identification (*IDN?).
+
+        Returns:
+            Identification string in format:
+            "Manufacturer,Model,SerialNumber,FirmwareVersion"
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If communication fails.
+        """
+        return self.query("*IDN?")
+
+    def reset(self) -> None:
+        """Reset instrument to default state (*RST).
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If communication fails.
+        """
+        self.write("*RST")
+
+    def clear_status(self) -> None:
+        """Clear instrument status (*CLS).
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If communication fails.
+        """
+        self.write("*CLS")
+
+    def operation_complete(self) -> bool:
+        """Query operation complete status (*OPC?).
+
+        Returns:
+            True if operation complete.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If communication fails.
+        """
+        response = self.query("*OPC?")
+        return response.strip() == "1"

src/py_dvt_ate/instruments/drivers/chamber.py

@@ -0,0 +1,142 @@
+"""Thermal chamber SCPI driver.
+
+This module implements a client-side driver for thermal chambers that
+communicate via SCPI commands.
+"""
+
+import time
+
+from py_dvt_ate.instruments.drivers.base import BaseDriver
+from py_dvt_ate.instruments.interfaces import IThermalChamber
+
+
+class ThermalChamberDriver(BaseDriver, IThermalChamber):
+    """SCPI driver for thermal chambers.
+
+    Provides high-level Python API for controlling thermal chambers via
+    SCPI commands. Implements the IThermalChamber interface.
+
+    SCPI Commands Used:
+        TEMP:SETPOINT <value>  - Set target temperature (°C)
+        TEMP:SETPOINT?         - Query current setpoint
+        TEMP:ACTUAL?           - Query actual chamber temperature
+        TEMP:STAB?             - Query stability (1=stable, 0=settling)
+        TEMP:RAMP <rate>       - Set temperature ramp rate (°C/min)
+        TEMP:RAMP?             - Query ramp rate
+
+    Example:
+        >>> transport = TCPTransport("localhost", 5001)
+        >>> chamber = ThermalChamberDriver(transport)
+        >>> chamber.connect()
+        >>> chamber.set_temperature(85.0)
+        >>> chamber.wait_until_stable(timeout=600.0)
+        >>> temp = chamber.get_temperature()
+    """
+
+    def set_temperature(self, setpoint: float) -> None:
+        """Set the chamber temperature setpoint.
+
+        Args:
+            setpoint: Target temperature in degrees Celsius.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If command fails.
+        """
+        self.write(f"TEMP:SETPOINT {setpoint:.2f}")
+
+    def get_temperature(self) -> float:
+        """Get the actual chamber temperature.
+
+        Returns:
+            Current chamber temperature in degrees Celsius.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+        """
+        return self.query_float("TEMP:ACTUAL?")
+
+    def get_setpoint(self) -> float:
+        """Get the current temperature setpoint.
+
+        Returns:
+            Current setpoint in degrees Celsius.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+        """
+        return self.query_float("TEMP:SETPOINT?")
+
+    def is_stable(self) -> bool:
+        """Check if chamber temperature is stable.
+
+        Temperature is considered stable when it has settled within
+        the instrument's configured stability threshold of the setpoint.
+
+        Returns:
+            True if temperature is stable, False if still settling.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+        """
+        return self.query_bool("TEMP:STAB?")
+
+    def wait_until_stable(
+        self, timeout: float = 300.0, poll_interval: float = 1.0
+    ) -> bool:
+        """Wait until chamber temperature stabilises.
+
+        Polls the stability status at regular intervals until stable
+        or timeout is reached.
+
+        Args:
+            timeout: Maximum time to wait in seconds. Default 300s (5 minutes).
+            poll_interval: Time between stability checks in seconds. Default 1s.
+
+        Returns:
+            True if temperature stabilised within timeout, False if timed out.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If communication fails.
+            ValueError: If timeout or poll_interval are negative.
+        """
+        if timeout < 0:
+            raise ValueError("Timeout must be non-negative")
+        if poll_interval <= 0:
+            raise ValueError("Poll interval must be positive")
+
+        start_time = time.time()
+        while time.time() - start_time < timeout:
+            if self.is_stable():
+                return True
+            time.sleep(poll_interval)
+
+        return False
+
+    def set_ramp_rate(self, rate: float) -> None:
+        """Set the temperature ramp rate.
+
+        Args:
+            rate: Ramp rate in degrees Celsius per minute.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If command fails.
+        """
+        self.write(f"TEMP:RAMP {rate:.2f}")
+
+    def get_ramp_rate(self) -> float:
+        """Get the current temperature ramp rate.
+
+        Returns:
+            Ramp rate in degrees Celsius per minute.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+        """
+        return self.query_float("TEMP:RAMP?")

src/py_dvt_ate/instruments/drivers/multimeter.py

@@ -0,0 +1,158 @@
+"""Multimeter SCPI driver.
+
+This module implements a client-side driver for digital multimeters
+that communicate via SCPI commands.
+"""
+
+from py_dvt_ate.instruments.drivers.base import BaseDriver
+from py_dvt_ate.instruments.interfaces import IMultimeter
+
+
+class MultimeterDriver(BaseDriver, IMultimeter):
+    """SCPI driver for digital multimeters.
+
+    Provides high-level Python API for making measurements with DMMs via
+    SCPI commands. Implements the IMultimeter interface.
+
+    SCPI Commands Used:
+        MEAS:VOLT:DC?      - Measure DC voltage
+        MEAS:CURR:DC?      - Measure DC current
+        CONF:VOLT:DC       - Configure for DC voltage measurement
+        CONF:CURR:DC       - Configure for DC current measurement
+        CONF?              - Query current configuration
+        READ?              - Take measurement with current configuration
+
+    Example:
+        >>> transport = TCPTransport("localhost", 5003)
+        >>> dmm = MultimeterDriver(transport)
+        >>> dmm.connect()
+        >>> voltage = dmm.measure_dc_voltage()
+        >>> current = dmm.measure_dc_current()
+    """
+
+    def measure_dc_voltage(self, range: str = "AUTO") -> float:
+        """Measure DC voltage.
+
+        Configures the meter for DC voltage and takes a measurement.
+
+        Args:
+            range: Measurement range. Default "AUTO" for auto-ranging.
+                  Note: Range parameter currently not supported by simulator.
+
+        Returns:
+            Measured voltage in volts.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+        """
+        # Note: Range parameter not yet implemented in virtual instrument
+        return self.query_float("MEAS:VOLT:DC?")
+
+    def measure_dc_current(self, range: str = "AUTO") -> float:
+        """Measure DC current.
+
+        Configures the meter for DC current and takes a measurement.
+
+        Args:
+            range: Measurement range. Default "AUTO" for auto-ranging.
+                  Note: Range parameter currently not supported by simulator.
+
+        Returns:
+            Measured current in amps.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+        """
+        # Note: Range parameter not yet implemented in virtual instrument
+        return self.query_float("MEAS:CURR:DC?")
+
+    def measure_resistance(self, range: str = "AUTO") -> float:
+        """Measure resistance.
+
+        Configures the meter for resistance and takes a measurement.
+
+        Args:
+            range: Measurement range. Default "AUTO" for auto-ranging.
+
+        Returns:
+            Measured resistance in ohms.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+            NotImplementedError: If instrument does not support resistance.
+        """
+        # Note: Resistance measurement not yet implemented in virtual instrument
+        raise NotImplementedError(
+            "Resistance measurement not yet supported by virtual instrument"
+        )
+
+    def set_integration_time(self, nplc: float) -> None:
+        """Set the integration time.
+
+        Args:
+            nplc: Integration time in number of power line cycles (NPLC).
+                 Typical values: 0.02, 0.2, 1, 10, 100.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If command fails.
+            NotImplementedError: If instrument does not support integration time.
+        """
+        # Note: Integration time not yet implemented in virtual instrument
+        raise NotImplementedError(
+            "Integration time setting not yet supported by virtual instrument"
+        )
+
+    def configure_dc_voltage(self) -> None:
+        """Configure meter for DC voltage measurement.
+
+        Sets the measurement function without taking a measurement.
+        Use read() to take a measurement after configuring.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If command fails.
+        """
+        self.write("CONF:VOLT:DC")
+
+    def configure_dc_current(self) -> None:
+        """Configure meter for DC current measurement.
+
+        Sets the measurement function without taking a measurement.
+        Use read() to take a measurement after configuring.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If command fails.
+        """
+        self.write("CONF:CURR:DC")
+
+    def get_configuration(self) -> str:
+        """Get the current measurement configuration.
+
+        Returns:
+            Configuration string (e.g., "VOLT:DC", "CURR:DC").
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+        """
+        return self.query("CONF?").strip('"')
+
+    def read(self) -> float:
+        """Take a measurement using the current configuration.
+
+        Must call configure_dc_voltage() or configure_dc_current() first
+        to set the measurement function.
+
+        Returns:
+            Measured value (voltage in V or current in A).
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+        """
+        return self.query_float("READ?")

src/py_dvt_ate/instruments/drivers/power_supply.py

@@ -0,0 +1,153 @@
+"""Power supply SCPI driver.
+
+This module implements a client-side driver for programmable power supplies
+that communicate via SCPI commands.
+"""
+
+from py_dvt_ate.instruments.drivers.base import BaseDriver
+from py_dvt_ate.instruments.interfaces import IPowerSupply
+
+
+class PowerSupplyDriver(BaseDriver, IPowerSupply):
+    """SCPI driver for programmable power supplies.
+
+    Provides high-level Python API for controlling power supplies via
+    SCPI commands. Implements the IPowerSupply interface.
+
+    Note: This driver assumes a single-channel instrument. The channel
+    parameter is accepted for interface compatibility but currently ignored.
+
+    SCPI Commands Used:
+        VOLT <value>       - Set output voltage (V)
+        VOLT?              - Query voltage setpoint
+        CURR <value>       - Set current limit (A)
+        CURR?              - Query current limit
+        OUTP <ON|OFF|1|0>  - Enable/disable output
+        OUTP?              - Query output state (1=on, 0=off)
+        MEAS:VOLT?         - Measure actual output voltage
+        MEAS:CURR?         - Measure actual output current
+
+    Example:
+        >>> transport = TCPTransport("localhost", 5002)
+        >>> psu = PowerSupplyDriver(transport)
+        >>> psu.connect()
+        >>> psu.set_voltage(1, 3.3)
+        >>> psu.set_current_limit(1, 0.5)
+        >>> psu.enable_output(1, True)
+        >>> voltage = psu.measure_voltage(1)
+    """
+
+    def set_voltage(self, channel: int, voltage: float) -> None:
+        """Set the output voltage setpoint.
+
+        Args:
+            channel: Channel number (currently ignored, single channel assumed).
+            voltage: Target voltage in volts.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If command fails.
+        """
+        self.write(f"VOLT {voltage:.3f}")
+
+    def get_voltage(self, channel: int) -> float:
+        """Get the voltage setpoint.
+
+        Args:
+            channel: Channel number (currently ignored, single channel assumed).
+
+        Returns:
+            Current voltage setpoint in volts.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+        """
+        return self.query_float("VOLT?")
+
+    def set_current_limit(self, channel: int, current: float) -> None:
+        """Set the current limit.
+
+        Args:
+            channel: Channel number (currently ignored, single channel assumed).
+            current: Current limit in amps.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If command fails.
+        """
+        self.write(f"CURR {current:.3f}")
+
+    def get_current_limit(self, channel: int) -> float:
+        """Get the current limit.
+
+        Args:
+            channel: Channel number (currently ignored, single channel assumed).
+
+        Returns:
+            Current limit in amps.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+        """
+        return self.query_float("CURR?")
+
+    def measure_voltage(self, channel: int) -> float:
+        """Measure the actual output voltage.
+
+        Args:
+            channel: Channel number (currently ignored, single channel assumed).
+
+        Returns:
+            Measured voltage in volts.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+        """
+        return self.query_float("MEAS:VOLT?")
+
+    def measure_current(self, channel: int) -> float:
+        """Measure the actual output current.
+
+        Args:
+            channel: Channel number (currently ignored, single channel assumed).
+
+        Returns:
+            Measured current in amps.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+        """
+        return self.query_float("MEAS:CURR?")
+
+    def enable_output(self, channel: int, enable: bool) -> None:
+        """Enable or disable the output.
+
+        Args:
+            channel: Channel number (currently ignored, single channel assumed).
+            enable: True to enable output, False to disable.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If command fails.
+        """
+        state = "ON" if enable else "OFF"
+        self.write(f"OUTP {state}")
+
+    def is_output_enabled(self, channel: int) -> bool:
+        """Check if output is enabled.
+
+        Args:
+            channel: Channel number (currently ignored, single channel assumed).
+
+        Returns:
+            True if output is enabled, False if disabled.
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If query fails.
+        """
+        return self.query_bool("OUTP?")

src/py_dvt_ate/instruments/factory.py

@@ -0,0 +1,176 @@
+"""Instrument factory for creating configured instrument sets.
+
+This module provides a factory pattern for creating sets of instruments
+based on configuration. It abstracts away the choice between simulated
+and real hardware, allowing test code to be written once and run against
+either backend.
+"""
+
+from dataclasses import dataclass
+from typing import Literal
+
+from py_dvt_ate.instruments.interfaces import IMultimeter, IPowerSupply, IThermalChamber
+
+
+@dataclass
+class InstrumentSet:
+    """Container for a complete set of instruments.
+
+    Holds all instruments needed for DVT testing. All instruments implement
+    the interface protocols (IThermalChamber, IPowerSupply, IMultimeter),
+    allowing them to be simulated or real hardware.
+
+    Attributes:
+        chamber: Thermal chamber for temperature control.
+        psu: Programmable power supply for DUT power.
+        dmm: Digital multimeter for precision measurements.
+    """
+
+    chamber: IThermalChamber
+    psu: IPowerSupply
+    dmm: IMultimeter
+
+
+@dataclass
+class InstrumentConfig:
+    """Configuration for instrument connections.
+
+    Defines how to connect to instruments. The backend determines whether
+    to use simulated instruments (TCP connections to virtual instruments)
+    or real hardware (PyVISA connections).
+
+    Attributes:
+        backend: "simulator" for virtual instruments, "pyvisa" for real hardware.
+
+        Simulator Settings:
+            simulator_host: Hostname/IP of simulation server. Default "localhost".
+            chamber_port: TCP port for thermal chamber simulator. Default 5001.
+            psu_port: TCP port for power supply simulator. Default 5002.
+            dmm_port: TCP port for multimeter simulator. Default 5003.
+
+        PyVISA Settings (for real hardware):
+            chamber_visa: VISA resource string for thermal chamber (e.g., "TCPIP::192.168.1.10::INSTR").
+            psu_visa: VISA resource string for power supply.
+            dmm_visa: VISA resource string for multimeter.
+    """
+
+    backend: Literal["simulator", "pyvisa"]
+
+    # Simulator settings
+    simulator_host: str = "localhost"
+    chamber_port: int = 5001
+    psu_port: int = 5002
+    dmm_port: int = 5003
+
+    # PyVISA settings (for real hardware)
+    chamber_visa: str | None = None
+    psu_visa: str | None = None
+    dmm_visa: str | None = None
+
+
+class InstrumentFactory:
+    """Factory for creating instrument sets from configuration.
+
+    This factory encapsulates the creation logic for instrument sets,
+    hiding the complexity of instantiating transports and drivers based
+    on the chosen backend.
+
+    Example:
+        >>> config = InstrumentConfig(backend="simulator")
+        >>> instruments = InstrumentFactory.create(config)
+        >>> instruments.chamber.set_temperature(85.0)
+        >>> instruments.psu.set_voltage(1, 3.3)
+        >>> voltage = instruments.dmm.measure_dc_voltage()
+    """
+
+    @staticmethod
+    def create(config: InstrumentConfig) -> InstrumentSet:
+        """Create instrument set based on configuration.
+
+        Args:
+            config: Configuration specifying backend and connection details.
+
+        Returns:
+            InstrumentSet containing all configured instruments.
+
+        Raises:
+            ValueError: If backend is unknown or configuration is invalid.
+            ConnectionError: If unable to connect to instruments.
+        """
+        if config.backend == "simulator":
+            return InstrumentFactory._create_simulated(config)
+        elif config.backend == "pyvisa":
+            return InstrumentFactory._create_pyvisa(config)
+        else:
+            raise ValueError(f"Unknown backend: {config.backend}")
+
+    @staticmethod
+    def _create_simulated(config: InstrumentConfig) -> InstrumentSet:
+        """Create simulated instruments connected via TCP.
+
+        Creates TCP transports for each virtual instrument and wraps them
+        in SCPI drivers. The simulation server must be running and listening
+        on the configured ports.
+
+        Args:
+            config: Configuration with simulator_host and port settings.
+
+        Returns:
+            InstrumentSet with simulated instruments.
+
+        Raises:
+            ConnectionError: If unable to connect to simulation server.
+        """
+        from py_dvt_ate.instruments.drivers.chamber import ThermalChamberDriver
+        from py_dvt_ate.instruments.drivers.multimeter import MultimeterDriver
+        from py_dvt_ate.instruments.drivers.power_supply import PowerSupplyDriver
+        from py_dvt_ate.instruments.transport.tcp import TCPTransport
+
+        # Create transports for each instrument
+        chamber_transport = TCPTransport(config.simulator_host, config.chamber_port)
+        psu_transport = TCPTransport(config.simulator_host, config.psu_port)
+        dmm_transport = TCPTransport(config.simulator_host, config.dmm_port)
+
+        # Wrap transports in drivers
+        return InstrumentSet(
+            chamber=ThermalChamberDriver(chamber_transport),
+            psu=PowerSupplyDriver(psu_transport),
+            dmm=MultimeterDriver(dmm_transport),
+        )
+
+    @staticmethod
+    def _create_pyvisa(config: InstrumentConfig) -> InstrumentSet:
+        """Create PyVISA instruments for real hardware.
+
+        Creates VISA transports for each real instrument and wraps them
+        in SCPI drivers. Requires PyVISA to be installed and VISA resource
+        strings to be configured.
+
+        Args:
+            config: Configuration with chamber_visa, psu_visa, dmm_visa settings.
+
+        Returns:
+            InstrumentSet with real hardware instruments.
+
+        Raises:
+            NotImplementedError: PyVISA backend not yet implemented.
+            ValueError: If required VISA resource strings are missing.
+        """
+        # Future implementation would use pyvisa.ResourceManager
+        # to create VISA transports:
+        #
+        # import pyvisa
+        # from py_dvt_ate.instruments.transport.visa import VISATransport
+        #
+        # rm = pyvisa.ResourceManager()
+        # chamber_transport = VISATransport(rm.open_resource(config.chamber_visa))
+        # psu_transport = VISATransport(rm.open_resource(config.psu_visa))
+        # dmm_transport = VISATransport(rm.open_resource(config.dmm_visa))
+        #
+        # return InstrumentSet(
+        #     chamber=ThermalChamberDriver(chamber_transport),
+        #     psu=PowerSupplyDriver(psu_transport),
+        #     dmm=MultimeterDriver(dmm_transport),
+        # )
+
+        raise NotImplementedError("PyVISA backend not yet implemented")

src/py_dvt_ate/instruments/interfaces.py

@@ -0,0 +1,362 @@
+"""Instrument interface protocols.
+
+This module defines the Hardware Abstraction Layer (HAL) interfaces for all
+laboratory instruments used in DVT testing. These protocols allow test code
+to be written against abstract interfaces rather than concrete implementations,
+enabling seamless switching between simulated and real hardware.
+
+The interfaces use ABC (Abstract Base Classes) for maximum type safety and
+explicit interface implementation. All drivers must inherit from these base
+classes and implement all abstract methods.
+"""
+
+from abc import ABC, abstractmethod
+
+
+class IThermalChamber(ABC):
+    """Hardware abstraction for thermal chambers.
+
+    Defines the interface for controlling environmental temperature during
+    thermal characterisation tests. Implementations may be virtual instruments
+    (simulators) or real hardware drivers.
+
+    Temperature units are always degrees Celsius.
+    """
+
+    @abstractmethod
+    def set_temperature(self, setpoint: float) -> None:
+        """Set the chamber temperature setpoint.
+
+        Args:
+            setpoint: Target temperature in degrees Celsius.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If command fails or instrument reports error.
+        """
+        pass
+
+    @abstractmethod
+    def get_temperature(self) -> float:
+        """Get the actual chamber temperature.
+
+        Returns:
+            Current chamber air temperature in degrees Celsius.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If query fails or instrument reports error.
+        """
+        pass
+
+    @abstractmethod
+    def get_setpoint(self) -> float:
+        """Get the current temperature setpoint.
+
+        Returns:
+            Current target temperature in degrees Celsius.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If query fails or instrument reports error.
+        """
+        pass
+
+    @abstractmethod
+    def is_stable(self) -> bool:
+        """Check if chamber temperature is stable.
+
+        Temperature is considered stable when it has settled within
+        the instrument's configured stability threshold of the setpoint
+        for a minimum dwell time.
+
+        Returns:
+            True if temperature is stable, False if still settling.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If query fails or instrument reports error.
+        """
+        pass
+
+    @abstractmethod
+    def wait_until_stable(
+        self, timeout: float = 300.0, poll_interval: float = 1.0
+    ) -> bool:
+        """Wait until chamber temperature stabilises.
+
+        Polls the stability status at regular intervals until stable
+        or timeout is reached. This is a blocking call.
+
+        Args:
+            timeout: Maximum time to wait in seconds. Default 300s (5 minutes).
+            poll_interval: Time between stability checks in seconds. Default 1s.
+
+        Returns:
+            True if temperature stabilised within timeout, False if timed out.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If communication fails.
+            ValueError: If timeout or poll_interval are invalid.
+        """
+        pass
+
+    @abstractmethod
+    def set_ramp_rate(self, rate: float) -> None:
+        """Set the temperature ramp rate.
+
+        Controls how quickly the chamber changes temperature when moving
+        to a new setpoint. Slower ramp rates reduce thermal shock to DUT.
+
+        Args:
+            rate: Ramp rate in degrees Celsius per minute.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If command fails or instrument reports error.
+            ValueError: If rate is negative or exceeds instrument limits.
+        """
+        pass
+
+
+class IPowerSupply(ABC):
+    """Hardware abstraction for programmable power supplies.
+
+    Defines the interface for controlling DC power supplies during electrical
+    characterisation tests. Implementations may be virtual instruments
+    (simulators) or real hardware drivers.
+
+    Voltage units are always volts (V).
+    Current units are always amps (A).
+    """
+
+    @abstractmethod
+    def set_voltage(self, channel: int, voltage: float) -> None:
+        """Set the output voltage setpoint.
+
+        Args:
+            channel: Output channel number (1-based indexing).
+            voltage: Target voltage in volts.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If command fails or instrument reports error.
+            ValueError: If channel is invalid or voltage out of range.
+        """
+        pass
+
+    @abstractmethod
+    def get_voltage(self, channel: int) -> float:
+        """Get the voltage setpoint.
+
+        Returns the programmed voltage, not the measured output voltage.
+        Use measure_voltage() to get the actual output voltage.
+
+        Args:
+            channel: Output channel number (1-based indexing).
+
+        Returns:
+            Current voltage setpoint in volts.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If query fails or instrument reports error.
+            ValueError: If channel is invalid.
+        """
+        pass
+
+    @abstractmethod
+    def set_current_limit(self, channel: int, current: float) -> None:
+        """Set the current limit.
+
+        The supply will operate in constant voltage mode until output current
+        reaches this limit, then transition to constant current mode.
+
+        Args:
+            channel: Output channel number (1-based indexing).
+            current: Current limit in amps.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If command fails or instrument reports error.
+            ValueError: If channel is invalid or current out of range.
+        """
+        pass
+
+    @abstractmethod
+    def get_current_limit(self, channel: int) -> float:
+        """Get the current limit.
+
+        Args:
+            channel: Output channel number (1-based indexing).
+
+        Returns:
+            Current limit in amps.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If query fails or instrument reports error.
+            ValueError: If channel is invalid.
+        """
+        pass
+
+    @abstractmethod
+    def measure_voltage(self, channel: int) -> float:
+        """Measure the actual output voltage.
+
+        Args:
+            channel: Output channel number (1-based indexing).
+
+        Returns:
+            Measured output voltage in volts.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If query fails or instrument reports error.
+            ValueError: If channel is invalid.
+        """
+        pass
+
+    @abstractmethod
+    def measure_current(self, channel: int) -> float:
+        """Measure the actual output current.
+
+        Args:
+            channel: Output channel number (1-based indexing).
+
+        Returns:
+            Measured output current in amps.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If query fails or instrument reports error.
+            ValueError: If channel is invalid.
+        """
+        pass
+
+    @abstractmethod
+    def enable_output(self, channel: int, enable: bool) -> None:
+        """Enable or disable the output.
+
+        Args:
+            channel: Output channel number (1-based indexing).
+            enable: True to enable output, False to disable.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If command fails or instrument reports error.
+            ValueError: If channel is invalid.
+        """
+        pass
+
+    @abstractmethod
+    def is_output_enabled(self, channel: int) -> bool:
+        """Check if output is enabled.
+
+        Args:
+            channel: Output channel number (1-based indexing).
+
+        Returns:
+            True if output is enabled, False if disabled.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If query fails or instrument reports error.
+            ValueError: If channel is invalid.
+        """
+        pass
+
+
+class IMultimeter(ABC):
+    """Hardware abstraction for digital multimeters.
+
+    Defines the interface for making precision measurements with DMMs during
+    electrical characterisation tests. Implementations may be virtual instruments
+    (simulators) or real hardware drivers.
+
+    Voltage units are always volts (V).
+    Current units are always amps (A).
+    Resistance units are always ohms (Ω).
+    """
+
+    @abstractmethod
+    def measure_dc_voltage(self, range: str = "AUTO") -> float:
+        """Measure DC voltage.
+
+        Configures the meter for DC voltage and takes a measurement.
+
+        Args:
+            range: Measurement range. Default "AUTO" for auto-ranging.
+                  Specific ranges depend on instrument capabilities.
+
+        Returns:
+            Measured voltage in volts.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If query fails or instrument reports error.
+            ValueError: If range is invalid for this instrument.
+        """
+        pass
+
+    @abstractmethod
+    def measure_dc_current(self, range: str = "AUTO") -> float:
+        """Measure DC current.
+
+        Configures the meter for DC current and takes a measurement.
+
+        Args:
+            range: Measurement range. Default "AUTO" for auto-ranging.
+                  Specific ranges depend on instrument capabilities.
+
+        Returns:
+            Measured current in amps.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If query fails or instrument reports error.
+            ValueError: If range is invalid for this instrument.
+        """
+        pass
+
+    @abstractmethod
+    def measure_resistance(self, range: str = "AUTO") -> float:
+        """Measure resistance.
+
+        Configures the meter for resistance and takes a measurement.
+
+        Args:
+            range: Measurement range. Default "AUTO" for auto-ranging.
+                  Specific ranges depend on instrument capabilities.
+
+        Returns:
+            Measured resistance in ohms.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If query fails or instrument reports error.
+            ValueError: If range is invalid for this instrument.
+            NotImplementedError: If instrument does not support resistance.
+        """
+        pass
+
+    @abstractmethod
+    def set_integration_time(self, nplc: float) -> None:
+        """Set the integration time.
+
+        Integration time affects measurement accuracy and speed. Higher
+        values (more power line cycles) provide better noise rejection
+        but take longer to measure.
+
+        Args:
+            nplc: Integration time in number of power line cycles (NPLC).
+                 Typical values: 0.02, 0.2, 1, 10, 100.
+
+        Raises:
+            ConnectionError: If not connected to instrument.
+            IOError: If command fails or instrument reports error.
+            ValueError: If nplc is invalid for this instrument.
+            NotImplementedError: If instrument does not support integration time.
+        """
+        pass

src/py_dvt_ate/instruments/scpi.py

@@ -0,0 +1,87 @@
+"""SCPI command parsing.
+
+This module provides SCPI (Standard Commands for Programmable Instruments)
+command parsing for instrument communication. It handles IEEE 488.2 common
+commands (*IDN?, *RST, etc.) and instrument-specific commands.
+"""
+
+from dataclasses import dataclass
+
+
+@dataclass
+class SCPICommand:
+    """Parsed SCPI command.
+
+    Attributes:
+        header: The command header (e.g., "TEMP:SETPOINT" or "*IDN").
+        arguments: List of command arguments (e.g., ["85.0"]).
+        is_query: True if the command ends with '?' (query command).
+    """
+
+    header: str
+    arguments: list[str]
+    is_query: bool
+
+    @property
+    def keyword(self) -> str:
+        """Return the command keyword without '?'.
+
+        For query commands like "TEMP:SETPOINT?", returns "TEMP:SETPOINT".
+        For regular commands like "VOLT", returns "VOLT".
+        """
+        return self.header.rstrip("?")
+
+
+class SCPIParser:
+    """Parse SCPI command strings.
+
+    Handles both IEEE 488.2 common commands (e.g., *IDN?, *RST) and
+    instrument-specific commands (e.g., VOLT 3.3, TEMP:SETPOINT?).
+
+    Examples:
+        >>> parser = SCPIParser()
+        >>> cmd = parser.parse("*IDN?")
+        >>> cmd.header, cmd.is_query
+        ('*IDN?', True)
+        >>> cmd = parser.parse("VOLT 3.3")
+        >>> cmd.header, cmd.arguments
+        ('VOLT', ['3.3'])
+    """
+
+    def parse(self, command_string: str) -> SCPICommand:
+        """Parse a SCPI command string.
+
+        Args:
+            command_string: The raw SCPI command string to parse.
+
+        Returns:
+            SCPICommand with parsed header, arguments, and query flag.
+
+        Examples:
+            "*IDN?" -> SCPICommand("*IDN?", [], True)
+            "VOLT 3.3" -> SCPICommand("VOLT", ["3.3"], False)
+            "TEMP:SETPOINT?" -> SCPICommand("TEMP:SETPOINT?", [], True)
+            "CONF:VOLT:DC 10,0.001" -> SCPICommand("CONF:VOLT:DC", ["10", "0.001"], False)
+        """
+        command_string = command_string.strip()
+        if not command_string:
+            return SCPICommand(header="", arguments=[], is_query=False)
+
+        # Split into header and arguments on first whitespace
+        parts = command_string.split(None, 1)
+        header = parts[0]
+        arguments: list[str] = []
+
+        if len(parts) > 1:
+            # Parse comma-separated arguments
+            arg_string = parts[1]
+            arguments = [arg.strip() for arg in arg_string.split(",")]
+
+        # Query is determined by whether the header ends with '?'
+        is_query = header.endswith("?")
+
+        return SCPICommand(
+            header=header,
+            arguments=arguments,
+            is_query=is_query,
+        )

src/py_dvt_ate/instruments/transport/__init__.py

@@ -1,6 +1,13 @@
 """Transport layer for instrument communication.
 
 Provides connection abstractions for different backends:
+- TCP server for hosting SCPI instruments
 - TCP sockets (for simulation server)
 - PyVISA (for real instruments)
 """
+
+from py_dvt_ate.instruments.transport.base import Transport
+from py_dvt_ate.instruments.transport.server import InstrumentServer, SCPIDevice
+from py_dvt_ate.instruments.transport.tcp import TCPTransport
+
+__all__ = ["Transport", "TCPTransport", "InstrumentServer", "SCPIDevice"]

src/py_dvt_ate/instruments/transport/base.py

@@ -0,0 +1,93 @@
+"""Base transport interface for instrument communication."""
+
+from abc import ABC, abstractmethod
+
+
+class Transport(ABC):
+    """Abstract transport interface for instrument communication.
+
+    This abstract base class defines the interface that all transport
+    implementations (TCP, VISA, etc.) must implement. It provides basic
+    connection management and communication primitives for SCPI-based
+    instruments.
+
+    Implementations must inherit from this class and implement all abstract
+    methods.
+    """
+
+    @abstractmethod
+    def connect(self) -> None:
+        """Establish connection to instrument.
+
+        Raises:
+            ConnectionError: If connection fails.
+        """
+        pass
+
+    @abstractmethod
+    def disconnect(self) -> None:
+        """Close connection to instrument.
+
+        Should be idempotent - safe to call multiple times.
+        """
+        pass
+
+    @abstractmethod
+    def write(self, command: str) -> None:
+        """Send command to instrument.
+
+        Args:
+            command: SCPI command string to send (without terminator).
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If write fails.
+        """
+        pass
+
+    @abstractmethod
+    def read(self, timeout: float | None = None) -> str:
+        """Read response from instrument.
+
+        Args:
+            timeout: Read timeout in seconds. None uses default.
+
+        Returns:
+            Response string from instrument (without terminator).
+
+        Raises:
+            ConnectionError: If not connected.
+            TimeoutError: If read times out.
+            IOError: If read fails.
+        """
+        pass
+
+    @abstractmethod
+    def query(self, command: str, timeout: float | None = None) -> str:
+        """Send command and read response.
+
+        Convenience method combining write() and read().
+
+        Args:
+            command: SCPI command string to send.
+            timeout: Read timeout in seconds. None uses default.
+
+        Returns:
+            Response string from instrument.
+
+        Raises:
+            ConnectionError: If not connected.
+            TimeoutError: If read times out.
+            IOError: If communication fails.
+        """
+        pass
+
+    @property
+    @abstractmethod
+    def is_connected(self) -> bool:
+        """Check if connection is active.
+
+        Returns:
+            True if connected, False otherwise.
+        """
+        pass

src/py_dvt_ate/instruments/transport/server.py

@@ -0,0 +1,237 @@
+"""Async TCP server for exposing instruments over network.
+
+This module provides the InstrumentServer class that hosts SCPI
+instruments over TCP, allowing client applications to communicate using
+standard SCPI commands over a network connection.
+
+This is a general-purpose server that works with any object implementing
+the SCPIDevice protocol (having a process(command) -> str method).
+"""
+
+from __future__ import annotations
+
+import asyncio
+import logging
+from functools import partial
+from typing import Protocol, runtime_checkable
+
+__all__ = ["InstrumentServer", "SCPIDevice"]
+
+logger = logging.getLogger(__name__)
+
+
+@runtime_checkable
+class SCPIDevice(Protocol):
+    """Protocol for SCPI-compatible devices.
+
+    Any object with a process method matching this signature can be
+    served by InstrumentServer.
+    """
+
+    def process(self, command: str) -> str:
+        """Process a SCPI command and return the response.
+
+        Args:
+            command: SCPI command string to process.
+
+        Returns:
+            Response string (may be empty for commands with no response).
+        """
+        ...
+
+
+class InstrumentServer:
+    """Async TCP server hosting SCPI instruments.
+
+    Each instrument is assigned a port. Clients connect via TCP and send
+    SCPI commands as newline-terminated strings. Responses are also
+    newline-terminated.
+
+    This server can host any device implementing the SCPIDevice protocol,
+    including both virtual instruments (simulators) and adapters for
+    real hardware.
+
+    Attributes:
+        host: Host address to bind to.
+    """
+
+    def __init__(self, host: str = "127.0.0.1") -> None:
+        """Initialise the instrument server.
+
+        Args:
+            host: Host address to bind to. Defaults to localhost.
+        """
+        self._host = host
+        self._instruments: dict[int, SCPIDevice] = {}
+        self._servers: list[asyncio.Server] = []
+        self._running = False
+
+    @property
+    def host(self) -> str:
+        """Get the host address."""
+        return self._host
+
+    @property
+    def is_running(self) -> bool:
+        """Check if server is currently running."""
+        return self._running
+
+    def register_instrument(self, port: int, instrument: SCPIDevice) -> None:
+        """Register an instrument to be served on a specific port.
+
+        Args:
+            port: TCP port number to serve the instrument on.
+            instrument: SCPI device to serve (any object with process method).
+
+        Raises:
+            ValueError: If port is already registered.
+            RuntimeError: If server is already running.
+        """
+        if self._running:
+            raise RuntimeError("Cannot register instruments while server is running")
+
+        if port in self._instruments:
+            raise ValueError(f"Port {port} is already registered")
+
+        self._instruments[port] = instrument
+        logger.info(
+            "Registered %s on port %d",
+            instrument.__class__.__name__,
+            port,
+        )
+
+    def get_instrument(self, port: int) -> SCPIDevice | None:
+        """Get the instrument registered on a port.
+
+        Args:
+            port: Port number to look up.
+
+        Returns:
+            Registered instrument, or None if port not registered.
+        """
+        return self._instruments.get(port)
+
+    @property
+    def registered_ports(self) -> list[int]:
+        """Get list of registered port numbers."""
+        return list(self._instruments.keys())
+
+    async def start(self) -> None:
+        """Start the server and begin listening on all registered ports.
+
+        Creates a TCP server for each registered instrument port.
+
+        Raises:
+            RuntimeError: If server is already running or no instruments registered.
+        """
+        if self._running:
+            raise RuntimeError("Server is already running")
+
+        if not self._instruments:
+            raise RuntimeError("No instruments registered")
+
+        self._running = True
+
+        for port, instrument in self._instruments.items():
+            handler = partial(self._handle_client, instrument=instrument, port=port)
+            server = await asyncio.start_server(
+                handler,
+                self._host,
+                port,
+            )
+            self._servers.append(server)
+            logger.info(
+                "Started server for %s on %s:%d",
+                instrument.__class__.__name__,
+                self._host,
+                port,
+            )
+
+    async def stop(self) -> None:
+        """Stop the server and close all connections."""
+        if not self._running:
+            return
+
+        for server in self._servers:
+            server.close()
+            await server.wait_closed()
+
+        self._servers.clear()
+        self._running = False
+        logger.info("Server stopped")
+
+    async def serve_forever(self) -> None:
+        """Start the server and run until cancelled.
+
+        This is a convenience method that starts the server and blocks
+        until the server is stopped or cancelled.
+        """
+        await self.start()
+        try:
+            # Keep running until cancelled
+            await asyncio.gather(
+                *[server.serve_forever() for server in self._servers]
+            )
+        finally:
+            await self.stop()
+
+    async def _handle_client(
+        self,
+        reader: asyncio.StreamReader,
+        writer: asyncio.StreamWriter,
+        instrument: SCPIDevice,
+        port: int,
+    ) -> None:
+        """Handle a client connection.
+
+        Reads SCPI commands (newline-terminated), processes them through
+        the instrument, and sends back responses (newline-terminated).
+
+        Args:
+            reader: Stream reader for incoming data.
+            writer: Stream writer for outgoing data.
+            instrument: The instrument to process commands.
+            port: Port number for logging.
+        """
+        addr = writer.get_extra_info("peername")
+        logger.info("Client connected to port %d from %s", port, addr)
+
+        try:
+            while True:
+                # Read until newline (SCPI line terminator)
+                data = await reader.readline()
+
+                if not data:
+                    # Client disconnected
+                    break
+
+                # Decode and strip whitespace
+                command = data.decode("utf-8").strip()
+
+                if not command:
+                    continue
+
+                logger.debug("Port %d received: %s", port, command)
+
+                # Process command through instrument
+                response = instrument.process(command)
+
+                # Send response with newline terminator
+                if response:
+                    writer.write(f"{response}\n".encode())
+                    await writer.drain()
+                    logger.debug("Port %d sent: %s", port, response)
+
+        except asyncio.CancelledError:
+            logger.debug("Client handler cancelled for port %d", port)
+        except ConnectionResetError:
+            logger.debug("Client connection reset on port %d", port)
+        except Exception as e:
+            logger.error("Error handling client on port %d: %s", port, e)
+        finally:
+            writer.close()
+            try:
+                await writer.wait_closed()
+            except Exception:
+                pass
+            logger.info("Client disconnected from port %d", port)

src/py_dvt_ate/instruments/transport/tcp.py

@@ -0,0 +1,195 @@
+"""TCP socket transport for instrument communication."""
+
+import socket
+from typing import Any
+
+from py_dvt_ate.instruments.transport.base import Transport
+
+
+class TCPTransport(Transport):
+    """TCP socket transport implementation.
+
+    Implements the Transport interface for communicating with SCPI
+    instruments over TCP/IP using newline-terminated messages.
+
+    Attributes:
+        host: Hostname or IP address of the instrument.
+        port: TCP port number.
+        timeout: Default socket timeout in seconds.
+    """
+
+    def __init__(
+        self,
+        host: str,
+        port: int,
+        timeout: float = 5.0,
+        encoding: str = "utf-8",
+    ) -> None:
+        """Initialise TCP transport.
+
+        Args:
+            host: Hostname or IP address.
+            port: TCP port number.
+            timeout: Default socket timeout in seconds.
+            encoding: Text encoding for commands and responses.
+        """
+        self._host = host
+        self._port = port
+        self._timeout = timeout
+        self._encoding = encoding
+        self._socket: socket.socket | None = None
+
+    @property
+    def host(self) -> str:
+        """Get the host address."""
+        return self._host
+
+    @property
+    def port(self) -> int:
+        """Get the port number."""
+        return self._port
+
+    @property
+    def is_connected(self) -> bool:
+        """Check if connection is active.
+
+        Returns:
+            True if connected, False otherwise.
+        """
+        return self._socket is not None
+
+    def connect(self) -> None:
+        """Establish connection to instrument.
+
+        Raises:
+            ConnectionError: If connection fails or already connected.
+        """
+        if self.is_connected:
+            raise ConnectionError("Already connected")
+
+        try:
+            self._socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            self._socket.settimeout(self._timeout)
+            self._socket.connect((self._host, self._port))
+        except OSError as err:
+            self._socket = None
+            raise ConnectionError(
+                f"Failed to connect to {self._host}:{self._port}: {err}"
+            ) from err
+
+    def disconnect(self) -> None:
+        """Close connection to instrument.
+
+        Safe to call multiple times (idempotent).
+        """
+        if self._socket is not None:
+            try:
+                self._socket.close()
+            except OSError:
+                pass  # Ignore errors during close
+            finally:
+                self._socket = None
+
+    def write(self, command: str) -> None:
+        """Send command to instrument.
+
+        Commands are sent with newline terminator appended.
+
+        Args:
+            command: SCPI command string to send (without terminator).
+
+        Raises:
+            ConnectionError: If not connected.
+            IOError: If write fails.
+        """
+        if not self.is_connected or self._socket is None:
+            raise ConnectionError("Not connected")
+
+        try:
+            message = f"{command}\n".encode(self._encoding)
+            self._socket.sendall(message)
+        except OSError as err:
+            raise OSError(f"Write failed: {err}") from err
+
+    def read(self, timeout: float | None = None) -> str:
+        """Read response from instrument.
+
+        Reads until newline terminator is received.
+
+        Args:
+            timeout: Read timeout in seconds. None uses default.
+
+        Returns:
+            Response string from instrument (without terminator).
+
+        Raises:
+            ConnectionError: If not connected.
+            TimeoutError: If read times out.
+            IOError: If read fails.
+        """
+        if not self.is_connected or self._socket is None:
+            raise ConnectionError("Not connected")
+
+        # Set timeout if specified
+        old_timeout = self._socket.gettimeout()
+        if timeout is not None:
+            self._socket.settimeout(timeout)
+
+        try:
+            # Read line by line (newline-terminated protocol)
+            response_bytes = b""
+            while True:
+                chunk = self._socket.recv(1)
+                if not chunk:
+                    raise ConnectionError("Connection closed by remote host")
+                response_bytes += chunk
+                if chunk == b"\n":
+                    break
+
+            # Decode and strip whitespace
+            return response_bytes.decode(self._encoding).strip()
+
+        except ConnectionError:
+            raise  # Re-raise ConnectionError as-is
+        except TimeoutError as err:
+            raise TimeoutError("Read timeout") from err
+        except (OSError, UnicodeDecodeError) as err:
+            raise OSError(f"Read failed: {err}") from err
+        finally:
+            # Restore original timeout
+            if timeout is not None:
+                self._socket.settimeout(old_timeout)
+
+    def query(self, command: str, timeout: float | None = None) -> str:
+        """Send command and read response.
+
+        Convenience method combining write() and read().
+
+        Args:
+            command: SCPI command string to send.
+            timeout: Read timeout in seconds. None uses default.
+
+        Returns:
+            Response string from instrument.
+
+        Raises:
+            ConnectionError: If not connected.
+            TimeoutError: If read times out.
+            IOError: If communication fails.
+        """
+        self.write(command)
+        return self.read(timeout)
+
+    def __enter__(self) -> "TCPTransport":
+        """Context manager entry."""
+        self.connect()
+        return self
+
+    def __exit__(self, *args: Any) -> None:
+        """Context manager exit."""
+        self.disconnect()
+
+    def __repr__(self) -> str:
+        """String representation."""
+        status = "connected" if self.is_connected else "disconnected"
+        return f"TCPTransport({self._host}:{self._port}, {status})"

src/py_dvt_ate/simulation/__init__.py

@@ -2,4 +2,10 @@
 
 Provides virtual instruments backed by a coupled thermal-electrical
 physics engine. Used for development and testing without real hardware.
+
+Note: InstrumentServer has moved to py_dvt_ate.instruments.transport
 """
+
+from py_dvt_ate.simulation.server import ServerConfig, SimulationServer
+
+__all__ = ["ServerConfig", "SimulationServer"]

src/py_dvt_ate/simulation/physics/models/base.py

@@ -1,15 +1,14 @@
-"""Base protocol for Device Under Test (DUT) models.
+"""Base interface for Device Under Test (DUT) models.
 
 Defines the interface that all DUT models must implement to integrate
 with the physics engine.
 """
 
-from typing import Protocol, runtime_checkable
+from abc import ABC, abstractmethod
 
 
-@runtime_checkable
+class DUTModel(ABC):
-class DUTModel(Protocol):
+    """Abstract base class for DUT electrical/thermal models.
-    """Protocol for DUT electrical/thermal models.
 
     DUT models encapsulate the temperature-dependent electrical behaviour
     of a device, enabling realistic simulation of thermal-electrical coupling.
@@ -18,8 +17,12 @@ class DUTModel(Protocol):
     All voltage parameters are in volts.
     All current parameters are in amps.
     All power parameters are in watts.
+
+    Implementations must inherit from this class and implement all abstract
+    methods.
     """
 
+    @abstractmethod
     def calculate_output_voltage(self, junction_temperature: float) -> float:
         """Calculate the output voltage at the given junction temperature.
 
@@ -29,8 +32,9 @@ class DUTModel(Protocol):
         Returns:
             Output voltage in volts.
         """
-        ...
+        pass
 
+    @abstractmethod
     def calculate_quiescent_current(self, junction_temperature: float) -> float:
         """Calculate the quiescent current at the given junction temperature.
 
@@ -40,8 +44,9 @@ class DUTModel(Protocol):
         Returns:
             Quiescent current in amps.
         """
-        ...
+        pass
 
+    @abstractmethod
     def calculate_power_dissipation(
         self,
         input_voltage: float,
@@ -58,4 +63,4 @@ class DUTModel(Protocol):
         Returns:
             Power dissipation in watts.
         """
-        ...
+        pass

src/py_dvt_ate/simulation/physics/models/ldo.py

@@ -7,6 +7,8 @@ and power dissipation calculations.
 
 from dataclasses import dataclass
 
+from py_dvt_ate.simulation.physics.models.base import DUTModel
+
 
 @dataclass(frozen=True)
 class LDOParameters:
@@ -35,7 +37,7 @@ class LDOParameters:
 REFERENCE_TEMPERATURE_C = 25.0
 
 
-class LDOModel:
+class LDOModel(DUTModel):
     """Temperature-dependent LDO voltage regulator model.
 
     Models the electrical behaviour of a linear voltage regulator with:
@@ -44,7 +46,7 @@ class LDOModel:
     - Dropout voltage that increases with temperature
     - Power dissipation from (Vin - Vout) × Iload + Vin × Iq
 
-    This class implements the DUTModel protocol.
+    This class implements the DUTModel interface.
     """
 
     def __init__(
@@ -194,7 +196,7 @@ class LDOModel:
         # Temperature ratio (reference is approximately 300K ≈ 27°C)
         temp_ratio = t_kelvin / 300.0
 
-        return self._params.dropout_voltage * (temp_ratio**1.5)
+        return float(self._params.dropout_voltage * (temp_ratio**1.5))
 
     def is_in_dropout(self, junction_temperature: float) -> bool:
         """Check if the LDO is in dropout at current operating point.

src/py_dvt_ate/simulation/server.py

@@ -0,0 +1,240 @@
+"""Simulation server entry point.
+
+This module provides the main entry point for running the simulation server
+with all virtual instruments wired to a shared physics engine.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import logging
+import signal
+from dataclasses import dataclass
+
+from py_dvt_ate.instruments.transport import InstrumentServer
+from py_dvt_ate.simulation.physics.engine import PhysicsEngine
+from py_dvt_ate.simulation.virtual.chamber import ThermalChamberSim
+from py_dvt_ate.simulation.virtual.multimeter import MultimeterSim
+from py_dvt_ate.simulation.virtual.power_supply import PowerSupplySim
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class ServerConfig:
+    """Configuration for the simulation server.
+
+    Attributes:
+        host: Host address to bind to.
+        chamber_port: Port for thermal chamber instrument.
+        psu_port: Port for power supply instrument.
+        dmm_port: Port for multimeter instrument.
+        physics_rate_hz: Physics engine update rate in Hz.
+    """
+
+    host: str = "127.0.0.1"
+    chamber_port: int = 5000
+    psu_port: int = 5001
+    dmm_port: int = 5002
+    physics_rate_hz: float = 100.0
+
+
+class SimulationServer:
+    """Complete simulation server with physics engine and instruments.
+
+    Creates a physics engine and wires it to all virtual instruments,
+    then exposes them over TCP for client access.
+    """
+
+    def __init__(self, config: ServerConfig | None = None) -> None:
+        """Initialise the simulation server.
+
+        Args:
+            config: Server configuration. Uses defaults if not provided.
+        """
+        self._config = config or ServerConfig()
+        self._physics_engine: PhysicsEngine | None = None
+        self._instrument_server: InstrumentServer | None = None
+        self._physics_task: asyncio.Task[None] | None = None
+        self._running = False
+
+    @property
+    def is_running(self) -> bool:
+        """Check if server is currently running."""
+        return self._running
+
+    @property
+    def physics_engine(self) -> PhysicsEngine | None:
+        """Get the physics engine instance."""
+        return self._physics_engine
+
+    def _setup(self) -> None:
+        """Create and wire up all components."""
+        # Create physics engine
+        self._physics_engine = PhysicsEngine(
+            update_rate_hz=self._config.physics_rate_hz
+        )
+
+        # Create instruments connected to physics engine
+        chamber = ThermalChamberSim(self._physics_engine)
+        psu = PowerSupplySim(self._physics_engine)
+        dmm = MultimeterSim(self._physics_engine)
+
+        # Create TCP server and register instruments
+        self._instrument_server = InstrumentServer(host=self._config.host)
+        self._instrument_server.register_instrument(self._config.chamber_port, chamber)
+        self._instrument_server.register_instrument(self._config.psu_port, psu)
+        self._instrument_server.register_instrument(self._config.dmm_port, dmm)
+
+        logger.info(
+            "Simulation server configured: chamber=%d, psu=%d, dmm=%d",
+            self._config.chamber_port,
+            self._config.psu_port,
+            self._config.dmm_port,
+        )
+
+    async def _run_physics(self) -> None:
+        """Run the physics engine simulation loop."""
+        if self._physics_engine is None:
+            return
+
+        dt = self._physics_engine.dt
+
+        while self._running:
+            self._physics_engine.step()
+            # Sleep for the physics timestep
+            await asyncio.sleep(dt)
+
+    async def start(self) -> None:
+        """Start the simulation server.
+
+        Sets up all components and starts the TCP server and physics engine.
+
+        Raises:
+            RuntimeError: If server is already running.
+        """
+        if self._running:
+            raise RuntimeError("Server is already running")
+
+        self._setup()
+        self._running = True
+
+        # Start TCP server
+        if self._instrument_server is not None:
+            await self._instrument_server.start()
+
+        # Start physics engine loop
+        self._physics_task = asyncio.create_task(self._run_physics())
+
+        logger.info("Simulation server started")
+
+    async def stop(self) -> None:
+        """Stop the simulation server."""
+        if not self._running:
+            return
+
+        self._running = False
+
+        # Cancel physics loop
+        if self._physics_task is not None:
+            self._physics_task.cancel()
+            try:
+                await self._physics_task
+            except asyncio.CancelledError:
+                pass
+            self._physics_task = None
+
+        # Stop TCP server
+        if self._instrument_server is not None:
+            await self._instrument_server.stop()
+            self._instrument_server = None
+
+        self._physics_engine = None
+        logger.info("Simulation server stopped")
+
+    async def serve_forever(self) -> None:
+        """Start the server and run until cancelled."""
+        await self.start()
+        try:
+            # Wait for the physics task (which runs until cancelled)
+            if self._physics_task is not None:
+                await self._physics_task
+        except asyncio.CancelledError:
+            pass
+        finally:
+            await self.stop()
+
+
+async def run_server(config: ServerConfig | None = None) -> None:
+    """Run the simulation server with signal handling.
+
+    This is the main entry point for running the server. It sets up
+    signal handlers for graceful shutdown.
+
+    Args:
+        config: Server configuration. Uses defaults if not provided.
+    """
+    server = SimulationServer(config)
+
+    # Set up signal handlers for graceful shutdown
+    loop = asyncio.get_running_loop()
+    stop_event = asyncio.Event()
+
+    def signal_handler() -> None:
+        logger.info("Shutdown signal received")
+        stop_event.set()
+
+    # Register signal handlers (Unix-style, may not work on all Windows)
+    try:
+        for sig in (signal.SIGINT, signal.SIGTERM):
+            loop.add_signal_handler(sig, signal_handler)
+    except NotImplementedError:
+        # Windows doesn't support add_signal_handler
+        pass
+
+    try:
+        await server.start()
+        logger.info("Simulation server running. Press Ctrl+C to stop.")
+
+        # Wait for stop signal
+        await stop_event.wait()
+    except KeyboardInterrupt:
+        logger.info("Keyboard interrupt received")
+    finally:
+        await server.stop()
+
+
+def main(
+    host: str = "127.0.0.1",
+    chamber_port: int = 5000,
+    psu_port: int = 5001,
+    dmm_port: int = 5002,
+    physics_rate: float = 100.0,
+) -> None:
+    """Run the simulation server from command line.
+
+    Args:
+        host: Host address to bind to.
+        chamber_port: Port for thermal chamber.
+        psu_port: Port for power supply.
+        dmm_port: Port for multimeter.
+        physics_rate: Physics engine update rate in Hz.
+    """
+    logging.basicConfig(
+        level=logging.INFO,
+        format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
+    )
+
+    config = ServerConfig(
+        host=host,
+        chamber_port=chamber_port,
+        psu_port=psu_port,
+        dmm_port=dmm_port,
+        physics_rate_hz=physics_rate,
+    )
+
+    asyncio.run(run_server(config))
+
+
+if __name__ == "__main__":
+    main()

src/py_dvt_ate/simulation/virtual/base.py

@@ -0,0 +1,156 @@
+"""Base class for virtual instrument simulators.
+
+This module provides the foundation for implementing SCPI-based virtual
+instruments that can be exposed over TCP for hardware abstraction testing.
+"""
+
+from __future__ import annotations
+
+from abc import ABC, abstractmethod
+from collections.abc import Callable
+from typing import TYPE_CHECKING
+
+from py_dvt_ate.instruments.scpi import SCPICommand, SCPIParser
+
+if TYPE_CHECKING:
+    from py_dvt_ate.simulation.physics.engine import PhysicsEngine
+
+
+# Type alias for command handlers
+CommandHandler = Callable[[SCPICommand], str]
+
+
+class BaseInstrument(ABC):
+    """Abstract base class for virtual SCPI instruments.
+
+    Provides common functionality for SCPI command parsing and dispatch.
+    Subclasses should register command handlers using the register_command
+    method or by overriding _setup_commands.
+
+    Attributes:
+        manufacturer: Instrument manufacturer name for *IDN? response.
+        model: Instrument model name for *IDN? response.
+        serial_number: Instrument serial number for *IDN? response.
+        firmware_version: Firmware version for *IDN? response.
+    """
+
+    manufacturer: str = "PyDVTATE"
+    model: str = "Virtual Instrument"
+    serial_number: str = "SIM001"
+    firmware_version: str = "1.0.0"
+
+    def __init__(self, physics_engine: PhysicsEngine | None = None) -> None:
+        """Initialise the base instrument.
+
+        Args:
+            physics_engine: Reference to physics engine for simulation state.
+                           May be None for standalone operation.
+        """
+        self._physics_engine = physics_engine
+        self._parser = SCPIParser()
+        self._handlers: dict[str, CommandHandler] = {}
+        self._setup_common_commands()
+        self._setup_commands()
+
+    def _setup_common_commands(self) -> None:
+        """Register IEEE 488.2 common commands."""
+        self.register_command("*IDN", self._handle_idn)
+        self.register_command("*RST", self._handle_rst)
+        self.register_command("*CLS", self._handle_cls)
+        self.register_command("*OPC", self._handle_opc)
+
+    @abstractmethod
+    def _setup_commands(self) -> None:
+        """Register instrument-specific command handlers.
+
+        Subclasses must implement this method to register their
+        SCPI command handlers using register_command().
+        """
+
+    def register_command(self, keyword: str, handler: CommandHandler) -> None:
+        """Register a handler for a SCPI command keyword.
+
+        Args:
+            keyword: The command keyword (e.g., "TEMP:SETPOINT").
+                    For commands that support both set and query forms,
+                    register the base keyword without '?'.
+            handler: Callable that takes SCPICommand and returns response string.
+        """
+        self._handlers[keyword.upper()] = handler
+
+    def process(self, command_string: str) -> str:
+        """Process a SCPI command string and return the response.
+
+        Args:
+            command_string: Raw SCPI command string to process.
+
+        Returns:
+            Response string. Empty string for commands with no response.
+            Error string starting with "ERROR:" for invalid commands.
+        """
+        command = self._parser.parse(command_string)
+
+        if not command.header:
+            return ""
+
+        # Look up handler by keyword (without '?' suffix)
+        keyword = command.keyword.upper()
+        handler = self._handlers.get(keyword)
+
+        if handler is None:
+            return f"ERROR: Unknown command '{keyword}'"
+
+        try:
+            return handler(command)
+        except ValueError as e:
+            return f"ERROR: {e}"
+        except Exception as e:
+            return f"ERROR: Internal error - {e}"
+
+    def _handle_idn(self, command: SCPICommand) -> str:
+        """Handle *IDN? identification query.
+
+        Returns:
+            Comma-separated identification string.
+        """
+        if not command.is_query:
+            return "ERROR: *IDN is query only"
+        return f"{self.manufacturer},{self.model},{self.serial_number},{self.firmware_version}"
+
+    def _handle_rst(self, command: SCPICommand) -> str:
+        """Handle *RST reset command.
+
+        Returns:
+            Empty string (no response for reset).
+        """
+        if command.is_query:
+            return "ERROR: *RST is command only"
+        self.reset()
+        return ""
+
+    def _handle_cls(self, command: SCPICommand) -> str:
+        """Handle *CLS clear status command.
+
+        Returns:
+            Empty string (no response for clear).
+        """
+        if command.is_query:
+            return "ERROR: *CLS is command only"
+        return ""
+
+    def _handle_opc(self, command: SCPICommand) -> str:
+        """Handle *OPC operation complete command/query.
+
+        Returns:
+            "1" for query, empty string for command.
+        """
+        if command.is_query:
+            return "1"
+        return ""
+
+    @abstractmethod
+    def reset(self) -> None:
+        """Reset instrument to default state.
+
+        Subclasses must implement this to define reset behaviour.
+        """

src/py_dvt_ate/simulation/virtual/chamber.py

@@ -0,0 +1,143 @@
+"""Virtual thermal chamber simulator.
+
+This module implements a SCPI-based virtual thermal chamber that interfaces
+with the physics engine to provide realistic temperature control simulation.
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from py_dvt_ate.instruments.scpi import SCPICommand
+from py_dvt_ate.simulation.virtual.base import BaseInstrument
+
+if TYPE_CHECKING:
+    from py_dvt_ate.simulation.physics.engine import PhysicsEngine
+
+
+class ThermalChamberSim(BaseInstrument):
+    """Virtual thermal chamber simulator.
+
+    Simulates a thermal chamber with SCPI control interface. The chamber
+    temperature behaviour is driven by the physics engine.
+
+    SCPI Commands:
+        TEMP:SETPOINT <value>  - Set target temperature in degrees C
+        TEMP:SETPOINT?         - Query current setpoint
+        TEMP:ACTUAL?           - Query actual chamber temperature
+        TEMP:STAB?             - Query temperature stability (1=stable, 0=settling)
+
+    Attributes:
+        manufacturer: "PyDVTATE"
+        model: "TC-SIM-001"
+    """
+
+    manufacturer = "PyDVTATE"
+    model = "TC-SIM-001"
+    serial_number = "TCSIM001"
+    firmware_version = "1.0.0"
+
+    # Stability threshold in degrees C
+    STABILITY_THRESHOLD = 0.5
+
+    def __init__(self, physics_engine: PhysicsEngine | None = None) -> None:
+        """Initialise the thermal chamber simulator.
+
+        Args:
+            physics_engine: Reference to physics engine for temperature state.
+        """
+        self._setpoint = 25.0  # Default setpoint
+        super().__init__(physics_engine)
+
+    def _setup_commands(self) -> None:
+        """Register thermal chamber SCPI commands."""
+        self.register_command("TEMP:SETPOINT", self._handle_temp_setpoint)
+        self.register_command("TEMP:ACTUAL", self._handle_temp_actual)
+        self.register_command("TEMP:STAB", self._handle_temp_stab)
+
+    def reset(self) -> None:
+        """Reset chamber to default state."""
+        self._setpoint = 25.0
+        if self._physics_engine is not None:
+            self._physics_engine.set_chamber_setpoint(self._setpoint)
+
+    def _handle_temp_setpoint(self, command: SCPICommand) -> str:
+        """Handle TEMP:SETPOINT command/query.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Setpoint value for query, empty string for set command.
+
+        Raises:
+            ValueError: If setpoint argument is invalid.
+        """
+        if command.is_query:
+            return f"{self._setpoint:.2f}"
+
+        # Set command requires one argument
+        if not command.arguments:
+            raise ValueError("TEMP:SETPOINT requires a value")
+
+        try:
+            setpoint = float(command.arguments[0])
+        except ValueError as err:
+            raise ValueError(f"Invalid temperature value: {command.arguments[0]}") from err
+
+        self._setpoint = setpoint
+        if self._physics_engine is not None:
+            self._physics_engine.set_chamber_setpoint(setpoint)
+
+        return ""
+
+    def _handle_temp_actual(self, command: SCPICommand) -> str:
+        """Handle TEMP:ACTUAL? query.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Actual chamber temperature.
+
+        Raises:
+            ValueError: If used as command (not query).
+        """
+        if not command.is_query:
+            raise ValueError("TEMP:ACTUAL is query only")
+
+        if self._physics_engine is None:
+            # Return setpoint if no physics engine connected
+            return f"{self._setpoint:.2f}"
+
+        thermal_state = self._physics_engine.get_thermal_state()
+        return f"{thermal_state.chamber_temperature:.2f}"
+
+    def _handle_temp_stab(self, command: SCPICommand) -> str:
+        """Handle TEMP:STAB? stability query.
+
+        Temperature is considered stable when the actual chamber temperature
+        is within STABILITY_THRESHOLD of the setpoint.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            "1" if stable, "0" if settling.
+
+        Raises:
+            ValueError: If used as command (not query).
+        """
+        if not command.is_query:
+            raise ValueError("TEMP:STAB is query only")
+
+        if self._physics_engine is None:
+            # Assume stable if no physics engine connected
+            return "1"
+
+        thermal_state = self._physics_engine.get_thermal_state()
+        error = abs(thermal_state.chamber_temperature - self._setpoint)
+
+        if error <= self.STABILITY_THRESHOLD:
+            return "1"
+        return "0"

src/py_dvt_ate/simulation/virtual/multimeter.py

@@ -0,0 +1,213 @@
+"""Virtual digital multimeter (DMM) simulator.
+
+This module implements a SCPI-based virtual multimeter that interfaces
+with the physics engine to measure DUT electrical parameters.
+"""
+
+from __future__ import annotations
+
+from enum import Enum
+from typing import TYPE_CHECKING
+
+from py_dvt_ate.instruments.scpi import SCPICommand
+from py_dvt_ate.simulation.virtual.base import BaseInstrument
+
+if TYPE_CHECKING:
+    from py_dvt_ate.simulation.physics.engine import PhysicsEngine
+
+
+class MeasurementFunction(Enum):
+    """Available measurement functions."""
+
+    VOLTAGE_DC = "VOLT:DC"
+    CURRENT_DC = "CURR:DC"
+
+
+class MultimeterSim(BaseInstrument):
+    """Virtual digital multimeter simulator.
+
+    Simulates a digital multimeter with SCPI control interface. The DMM
+    measures DUT output voltage and load current via the physics engine.
+
+    SCPI Commands:
+        MEAS:VOLT:DC?      - Measure DC voltage (shortcut)
+        MEAS:CURR:DC?      - Measure DC current (shortcut)
+        CONF:VOLT:DC       - Configure for DC voltage measurement
+        CONF:CURR:DC       - Configure for DC current measurement
+        CONF?              - Query current configuration
+        READ?              - Take measurement with current configuration
+
+    Attributes:
+        manufacturer: "PyDVTATE"
+        model: "DMM-SIM-001"
+    """
+
+    manufacturer = "PyDVTATE"
+    model = "DMM-SIM-001"
+    serial_number = "DMMSIM001"
+    firmware_version = "1.0.0"
+
+    def __init__(self, physics_engine: PhysicsEngine | None = None) -> None:
+        """Initialise the multimeter simulator.
+
+        Args:
+            physics_engine: Reference to physics engine for measurement values.
+        """
+        self._function = MeasurementFunction.VOLTAGE_DC
+        super().__init__(physics_engine)
+
+    def _setup_commands(self) -> None:
+        """Register multimeter SCPI commands."""
+        self.register_command("MEAS:VOLT:DC", self._handle_meas_volt_dc)
+        self.register_command("MEAS:CURR:DC", self._handle_meas_curr_dc)
+        self.register_command("CONF:VOLT:DC", self._handle_conf_volt_dc)
+        self.register_command("CONF:CURR:DC", self._handle_conf_curr_dc)
+        self.register_command("CONF", self._handle_conf)
+        self.register_command("READ", self._handle_read)
+
+    def reset(self) -> None:
+        """Reset multimeter to default state."""
+        self._function = MeasurementFunction.VOLTAGE_DC
+
+    def _handle_meas_volt_dc(self, command: SCPICommand) -> str:
+        """Handle MEAS:VOLT:DC? query.
+
+        Configures for DC voltage and takes measurement in one command.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Measured DC voltage.
+
+        Raises:
+            ValueError: If used as command (not query).
+        """
+        if not command.is_query:
+            raise ValueError("MEAS:VOLT:DC is query only")
+
+        self._function = MeasurementFunction.VOLTAGE_DC
+        return self._measure_voltage_dc()
+
+    def _handle_meas_curr_dc(self, command: SCPICommand) -> str:
+        """Handle MEAS:CURR:DC? query.
+
+        Configures for DC current and takes measurement in one command.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Measured DC current.
+
+        Raises:
+            ValueError: If used as command (not query).
+        """
+        if not command.is_query:
+            raise ValueError("MEAS:CURR:DC is query only")
+
+        self._function = MeasurementFunction.CURRENT_DC
+        return self._measure_current_dc()
+
+    def _handle_conf_volt_dc(self, command: SCPICommand) -> str:
+        """Handle CONF:VOLT:DC command.
+
+        Configures multimeter for DC voltage measurement.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Empty string (no response for configuration).
+
+        Raises:
+            ValueError: If used as query.
+        """
+        if command.is_query:
+            raise ValueError("CONF:VOLT:DC is command only")
+
+        self._function = MeasurementFunction.VOLTAGE_DC
+        return ""
+
+    def _handle_conf_curr_dc(self, command: SCPICommand) -> str:
+        """Handle CONF:CURR:DC command.
+
+        Configures multimeter for DC current measurement.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Empty string (no response for configuration).
+
+        Raises:
+            ValueError: If used as query.
+        """
+        if command.is_query:
+            raise ValueError("CONF:CURR:DC is command only")
+
+        self._function = MeasurementFunction.CURRENT_DC
+        return ""
+
+    def _handle_conf(self, command: SCPICommand) -> str:
+        """Handle CONF? query.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Current measurement configuration.
+
+        Raises:
+            ValueError: If used as command without subcommand.
+        """
+        if not command.is_query:
+            raise ValueError("CONF requires a function (e.g., CONF:VOLT:DC)")
+
+        return f'"{self._function.value}"'
+
+    def _handle_read(self, command: SCPICommand) -> str:
+        """Handle READ? query.
+
+        Takes measurement using current configuration.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Measured value.
+
+        Raises:
+            ValueError: If used as command (not query).
+        """
+        if not command.is_query:
+            raise ValueError("READ is query only")
+
+        if self._function == MeasurementFunction.VOLTAGE_DC:
+            return self._measure_voltage_dc()
+        else:
+            return self._measure_current_dc()
+
+    def _measure_voltage_dc(self) -> str:
+        """Measure DC voltage from physics engine.
+
+        Returns:
+            Formatted voltage reading.
+        """
+        if self._physics_engine is None:
+            return "0.000000"
+
+        electrical_state = self._physics_engine.get_electrical_state()
+        return f"{electrical_state.output_voltage:.6f}"
+
+    def _measure_current_dc(self) -> str:
+        """Measure DC current from physics engine.
+
+        Returns:
+            Formatted current reading.
+        """
+        if self._physics_engine is None:
+            return "0.000000"
+
+        electrical_state = self._physics_engine.get_electrical_state()
+        return f"{electrical_state.load_current:.6f}"

src/py_dvt_ate/simulation/virtual/power_supply.py

@@ -0,0 +1,222 @@
+"""Virtual power supply simulator.
+
+This module implements a SCPI-based virtual power supply that interfaces
+with the physics engine to provide realistic power supply simulation.
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from py_dvt_ate.instruments.scpi import SCPICommand
+from py_dvt_ate.simulation.virtual.base import BaseInstrument
+
+if TYPE_CHECKING:
+    from py_dvt_ate.simulation.physics.engine import PhysicsEngine
+
+
+class PowerSupplySim(BaseInstrument):
+    """Virtual power supply simulator.
+
+    Simulates a programmable DC power supply with SCPI control interface.
+    The power supply provides input voltage to the DUT via the physics engine.
+
+    SCPI Commands:
+        VOLT <value>       - Set output voltage in volts
+        VOLT?              - Query voltage setpoint
+        CURR <value>       - Set current limit in amps
+        CURR?              - Query current limit
+        OUTP <ON|OFF|1|0>  - Enable/disable output
+        OUTP?              - Query output state (1=on, 0=off)
+        MEAS:VOLT?         - Measure actual output voltage
+        MEAS:CURR?         - Measure actual output current
+
+    Attributes:
+        manufacturer: "PyDVTATE"
+        model: "PS-SIM-001"
+    """
+
+    manufacturer = "PyDVTATE"
+    model = "PS-SIM-001"
+    serial_number = "PSSIM001"
+    firmware_version = "1.0.0"
+
+    # Default values
+    DEFAULT_VOLTAGE = 0.0
+    DEFAULT_CURRENT_LIMIT = 1.0
+
+    def __init__(self, physics_engine: PhysicsEngine | None = None) -> None:
+        """Initialise the power supply simulator.
+
+        Args:
+            physics_engine: Reference to physics engine for electrical state.
+        """
+        self._voltage_setpoint = self.DEFAULT_VOLTAGE
+        self._current_limit = self.DEFAULT_CURRENT_LIMIT
+        self._output_enabled = False
+        super().__init__(physics_engine)
+
+    def _setup_commands(self) -> None:
+        """Register power supply SCPI commands."""
+        self.register_command("VOLT", self._handle_volt)
+        self.register_command("CURR", self._handle_curr)
+        self.register_command("OUTP", self._handle_outp)
+        self.register_command("MEAS:VOLT", self._handle_meas_volt)
+        self.register_command("MEAS:CURR", self._handle_meas_curr)
+
+    def reset(self) -> None:
+        """Reset power supply to default state."""
+        self._voltage_setpoint = self.DEFAULT_VOLTAGE
+        self._current_limit = self.DEFAULT_CURRENT_LIMIT
+        self._output_enabled = False
+
+        if self._physics_engine is not None:
+            self._physics_engine.set_input_voltage(0.0)
+            self._physics_engine.set_output_enabled(False)
+
+    def _handle_volt(self, command: SCPICommand) -> str:
+        """Handle VOLT command/query.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Voltage setpoint for query, empty string for set command.
+
+        Raises:
+            ValueError: If voltage argument is invalid.
+        """
+        if command.is_query:
+            return f"{self._voltage_setpoint:.3f}"
+
+        if not command.arguments:
+            raise ValueError("VOLT requires a value")
+
+        try:
+            voltage = float(command.arguments[0])
+        except ValueError as err:
+            raise ValueError(f"Invalid voltage value: {command.arguments[0]}") from err
+
+        if voltage < 0:
+            raise ValueError("Voltage cannot be negative")
+
+        self._voltage_setpoint = voltage
+
+        if self._physics_engine is not None and self._output_enabled:
+            self._physics_engine.set_input_voltage(voltage)
+
+        return ""
+
+    def _handle_curr(self, command: SCPICommand) -> str:
+        """Handle CURR command/query.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Current limit for query, empty string for set command.
+
+        Raises:
+            ValueError: If current argument is invalid.
+        """
+        if command.is_query:
+            return f"{self._current_limit:.3f}"
+
+        if not command.arguments:
+            raise ValueError("CURR requires a value")
+
+        try:
+            current = float(command.arguments[0])
+        except ValueError as err:
+            raise ValueError(f"Invalid current value: {command.arguments[0]}") from err
+
+        if current < 0:
+            raise ValueError("Current limit cannot be negative")
+
+        self._current_limit = current
+        return ""
+
+    def _handle_outp(self, command: SCPICommand) -> str:
+        """Handle OUTP command/query.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            "1" or "0" for query, empty string for set command.
+
+        Raises:
+            ValueError: If output argument is invalid.
+        """
+        if command.is_query:
+            return "1" if self._output_enabled else "0"
+
+        if not command.arguments:
+            raise ValueError("OUTP requires a value (ON, OFF, 1, or 0)")
+
+        arg = command.arguments[0].upper()
+        if arg in ("ON", "1"):
+            self._output_enabled = True
+        elif arg in ("OFF", "0"):
+            self._output_enabled = False
+        else:
+            raise ValueError(f"Invalid output state: {command.arguments[0]}")
+
+        if self._physics_engine is not None:
+            self._physics_engine.set_output_enabled(self._output_enabled)
+            if self._output_enabled:
+                self._physics_engine.set_input_voltage(self._voltage_setpoint)
+            else:
+                self._physics_engine.set_input_voltage(0.0)
+
+        return ""
+
+    def _handle_meas_volt(self, command: SCPICommand) -> str:
+        """Handle MEAS:VOLT? query.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Measured output voltage.
+
+        Raises:
+            ValueError: If used as command (not query).
+        """
+        if not command.is_query:
+            raise ValueError("MEAS:VOLT is query only")
+
+        if not self._output_enabled:
+            return "0.000"
+
+        if self._physics_engine is None:
+            return f"{self._voltage_setpoint:.3f}"
+
+        electrical_state = self._physics_engine.get_electrical_state()
+        return f"{electrical_state.input_voltage:.3f}"
+
+    def _handle_meas_curr(self, command: SCPICommand) -> str:
+        """Handle MEAS:CURR? query.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Measured output current.
+
+        Raises:
+            ValueError: If used as command (not query).
+        """
+        if not command.is_query:
+            raise ValueError("MEAS:CURR is query only")
+
+        if not self._output_enabled:
+            return "0.000"
+
+        if self._physics_engine is None:
+            return "0.000"
+
+        electrical_state = self._physics_engine.get_electrical_state()
+        # Total current is load current + quiescent current
+        total_current = electrical_state.load_current + electrical_state.quiescent_current
+        return f"{total_current:.3f}"

src/py_dvt_ate/tests/base.py

@@ -0,0 +1,158 @@
+"""Base class and utilities for DVT test implementations.
+
+This module provides common functionality shared across all DVT tests,
+including thermal settling helpers, measurement utilities, and statistical
+calculations.
+"""
+
+import time
+from abc import ABC
+from collections.abc import Callable
+
+from py_dvt_ate.framework.context import ITest, TestContext
+
+
+class BaseDVTTest(ITest, ABC):
+    """Abstract base class for DVT tests with common utilities.
+
+    Provides helper methods for thermal settling, measurement averaging,
+    and other common test patterns. All DVT tests should inherit from
+    this class rather than directly from ITest.
+    """
+
+    def wait_for_temperature(
+        self,
+        context: TestContext,
+        setpoint: float,
+        timeout: float = 300.0,
+        poll_interval: float = 1.0,
+    ) -> bool:
+        """Wait for thermal chamber to stabilise at setpoint.
+
+        Sets the chamber temperature and waits until stable. Logs progress
+        to the test logger.
+
+        Args:
+            context: Test context with instruments and logger.
+            setpoint: Target temperature in degrees Celsius.
+            timeout: Maximum wait time in seconds. Default 300s (5 minutes).
+            poll_interval: Time between stability checks. Default 1s.
+
+        Returns:
+            True if temperature stabilised within timeout, False if timed out.
+
+        Raises:
+            ConnectionError: If instrument communication fails.
+            IOError: If instrument reports error.
+        """
+        chamber = context.instruments.chamber
+
+        # Set the temperature
+        chamber.set_temperature(setpoint)
+        context.logger.log_event(
+            f"Set thermal chamber to {setpoint:.1f}°C, waiting for stability...",
+            level="INFO",
+        )
+
+        # Wait for stability
+        start_time = time.time()
+        elapsed = 0.0
+
+        while elapsed < timeout:
+            if chamber.is_stable():
+                actual = chamber.get_temperature()
+                context.logger.log_event(
+                    f"Chamber stable at {actual:.2f}°C "
+                    f"(target {setpoint:.1f}°C) after {elapsed:.1f}s",
+                    level="INFO",
+                )
+                return True
+
+            time.sleep(poll_interval)
+            elapsed = time.time() - start_time
+
+        # Timeout
+        actual = chamber.get_temperature()
+        context.logger.log_event(
+            f"Timeout waiting for stability. Chamber at {actual:.2f}°C, "
+            f"target {setpoint:.1f}°C after {timeout:.1f}s",
+            level="WARNING",
+        )
+        return False
+
+    def measure_averaged(
+        self,
+        measurement_func: Callable[[], float],
+        num_samples: int = 5,
+        settle_time: float = 0.1,
+    ) -> tuple[float, float]:
+        """Take multiple measurements and return mean and standard deviation.
+
+        Useful for reducing noise in measurements by averaging multiple samples.
+
+        Args:
+            measurement_func: Function that returns a single measurement.
+            num_samples: Number of samples to average. Default 5.
+            settle_time: Delay between samples in seconds. Default 0.1s.
+
+        Returns:
+            Tuple of (mean, standard_deviation).
+
+        Raises:
+            ValueError: If num_samples < 1.
+            Exception: If measurement_func raises an exception.
+        """
+        if num_samples < 1:
+            raise ValueError("num_samples must be at least 1")
+
+        samples: list[float] = []
+        for _ in range(num_samples):
+            if settle_time > 0 and len(samples) > 0:
+                time.sleep(settle_time)
+            samples.append(measurement_func())
+
+        mean = sum(samples) / len(samples)
+
+        if len(samples) == 1:
+            std_dev = 0.0
+        else:
+            variance = sum((x - mean) ** 2 for x in samples) / (len(samples) - 1)
+            std_dev = variance ** 0.5
+
+        return mean, std_dev
+
+    def thermal_settle(
+        self,
+        context: TestContext,
+        additional_settle_time: float = 5.0,
+    ) -> None:
+        """Wait for additional thermal settling after chamber reports stable.
+
+        After the chamber reports stable temperature, this adds additional
+        settling time to ensure the DUT junction temperature has also stabilised.
+        This is important for measurements sensitive to self-heating effects.
+
+        Args:
+            context: Test context with logger.
+            additional_settle_time: Extra settling time in seconds. Default 5s.
+        """
+        if additional_settle_time > 0:
+            context.logger.log_event(
+                f"Additional thermal settling for {additional_settle_time:.1f}s...",
+                level="INFO",
+            )
+            time.sleep(additional_settle_time)
+
+    def delay(self, seconds: float, message: str | None = None) -> None:
+        """Sleep for specified duration.
+
+        Simple utility for adding delays in test sequences.
+
+        Args:
+            seconds: Delay duration in seconds.
+            message: Optional message describing reason for delay.
+        """
+        if message:
+            # Could log this if needed
+            pass
+        time.sleep(seconds)

src/py_dvt_ate/tests/thermal/tempco.py

@@ -0,0 +1,243 @@
+"""Temperature Coefficient (TempCo) characterisation test.
+
+This test characterises the output voltage temperature coefficient by
+sweeping the chamber temperature and measuring output voltage at each point.
+The TempCo is calculated from the linear regression slope and expressed
+in parts per million per degree Celsius (ppm/°C).
+"""
+
+from py_dvt_ate.data.models import TestStatus
+from py_dvt_ate.framework.context import TestContext
+from py_dvt_ate.tests.base import BaseDVTTest
+
+
+class TempCoTest(BaseDVTTest):
+    """Temperature coefficient characterisation test.
+
+    Measures how output voltage varies with temperature. This is a critical
+    parameter for voltage regulators, as it indicates stability across
+    the operating temperature range.
+
+    Test Procedure:
+        1. Configure DUT supply voltage and load current
+        2. Sweep chamber temperature from min to max
+        3. At each temperature point:
+           - Wait for thermal stability
+           - Measure output voltage (averaged)
+           - Log measurement with conditions
+        4. Calculate TempCo from linear regression
+        5. Evaluate against specification limits
+
+    Configuration:
+        temperatures: List of temperature points (°C). Default: [-40, -20, 0, 25, 50, 85]
+        input_voltage: DUT input voltage (V). Default: 5.0
+        load_current: DUT load current (A). Default: 0.1
+        settle_time: Additional settling time at each temp (s). Default: 5.0
+        num_samples: Number of measurements to average per point. Default: 5
+        tempco_limit: Maximum allowed TempCo magnitude (ppm/°C). Default: ±50.0
+    """
+
+    @property
+    def name(self) -> str:
+        """Return test identifier."""
+        return "tempco"
+
+    @property
+    def description(self) -> str:
+        """Return test description."""
+        return "Output voltage temperature coefficient"
+
+    def execute(self, context: TestContext) -> TestStatus:
+        """Execute TempCo characterisation test.
+
+        Args:
+            context: Test context with instruments, logger, and configuration.
+
+        Returns:
+            PASSED if TempCo is within limits, FAILED otherwise.
+            ERROR if a critical failure occurs.
+        """
+        try:
+            # Get configuration
+            config = context.config
+            temperatures = config.get("temperatures", [-40.0, -20.0, 0.0, 25.0, 50.0, 85.0])
+            input_voltage = config.get("input_voltage", 5.0)
+            load_current = config.get("load_current", 0.1)
+            settle_time = config.get("settle_time", 5.0)
+            num_samples = config.get("num_samples", 5)
+            tempco_limit = config.get("tempco_limit", 50.0)
+
+            context.logger.log_event(
+                f"Starting TempCo test: {len(temperatures)} temperature points, "
+                f"Vin={input_voltage}V, Iload={load_current}A",
+                level="INFO",
+            )
+
+            # Configure DUT power
+            context.logger.log_event(
+                f"Configuring PSU: Vin={input_voltage}V, Ilimit={load_current + 0.5}A",
+                level="INFO",
+            )
+            psu = context.instruments.psu
+            psu.set_voltage(1, input_voltage)
+            psu.set_current_limit(1, load_current + 0.5)  # Add headroom
+            psu.enable_output(1, True)
+
+            # Storage for measurements
+            temp_points: list[float] = []
+            vout_points: list[float] = []
+
+            # Temperature sweep
+            for temp_setpoint in temperatures:
+                context.logger.log_event(
+                    f"Temperature point: {temp_setpoint}°C",
+                    level="INFO",
+                )
+
+                # Wait for thermal stability
+                stable = self.wait_for_temperature(
+                    context,
+                    temp_setpoint,
+                    timeout=300.0,
+                )
+                if not stable:
+                    context.logger.log_event(
+                        f"Warning: Temperature did not stabilise at {temp_setpoint}°C",
+                        level="WARNING",
+                    )
+
+                # Additional settling for DUT junction temperature
+                self.thermal_settle(context, settle_time)
+
+                # Measure output voltage (averaged)
+                actual_temp = context.instruments.chamber.get_temperature()
+
+                def measure_vout() -> float:
+                    return context.instruments.dmm.measure_dc_voltage()
+
+                vout_mean, vout_std = self.measure_averaged(
+                    measure_vout,
+                    num_samples=num_samples,
+                )
+
+                # Log individual measurement
+                context.logger.log_measurement(
+                    parameter="v_out",
+                    value=vout_mean,
+                    unit="V",
+                    conditions={
+                        "temperature": actual_temp,
+                        "input_voltage": input_voltage,
+                        "load_current": load_current,
+                    },
+                )
+
+                context.logger.log_event(
+                    f"Measured Vout = {vout_mean:.6f}V ± {vout_std * 1e6:.1f}μV "
+                    f"at T={actual_temp:.2f}°C",
+                    level="INFO",
+                )
+
+                # Store for TempCo calculation
+                temp_points.append(actual_temp)
+                vout_points.append(vout_mean)
+
+            # Calculate TempCo from linear regression
+            tempco_ppm = self._calculate_tempco(temp_points, vout_points)
+
+            context.logger.log_event(
+                f"Calculated TempCo = {tempco_ppm:.2f} ppm/°C",
+                level="INFO",
+            )
+
+            # Log result with limits
+            context.logger.log_result(
+                parameter="temp_co",
+                value=tempco_ppm,
+                unit="ppm/°C",
+                lower_limit=-abs(tempco_limit),
+                upper_limit=abs(tempco_limit),
+            )
+
+            # Evaluate pass/fail
+            passed = abs(tempco_ppm) <= tempco_limit
+
+            if passed:
+                context.logger.log_event(
+                    f"TempCo test PASSED: {tempco_ppm:.2f} ppm/°C within ±{tempco_limit} ppm/°C",
+                    level="INFO",
+                )
+                return TestStatus.PASSED
+            else:
+                context.logger.log_event(
+                    f"TempCo test FAILED: {tempco_ppm:.2f} ppm/°C exceeds ±{tempco_limit} ppm/°C",
+                    level="ERROR",
+                )
+                return TestStatus.FAILED
+
+        except Exception as e:
+            context.logger.log_event(
+                f"TempCo test ERROR: {e!s}",
+                level="ERROR",
+            )
+            return TestStatus.ERROR
+
+        finally:
+            # Cleanup: disable PSU output
+            try:
+                context.instruments.psu.enable_output(1, False)
+                context.logger.log_event("PSU output disabled", level="INFO")
+            except Exception:
+                pass  # Best effort cleanup
+
+    def _calculate_tempco(
+        self,
+        temperatures: list[float],
+        voltages: list[float],
+    ) -> float:
+        """Calculate temperature coefficient from measurements.
+
+        Uses linear regression to find the slope (dV/dT), then converts
+        to ppm/°C relative to the nominal voltage (voltage at median temperature).
+
+        Args:
+            temperatures: Temperature measurements in °C.
+            voltages: Output voltage measurements in V.
+
+        Returns:
+            Temperature coefficient in ppm/°C.
+
+        Raises:
+            ValueError: If insufficient data points.
+        """
+        if len(temperatures) < 2 or len(temperatures) != len(voltages):
+            raise ValueError("Need at least 2 matching temperature-voltage pairs")
+
+        n = len(temperatures)
+
+        # Linear regression: V = a + b*T
+        # We want slope b = dV/dT
+        mean_t = sum(temperatures) / n
+        mean_v = sum(voltages) / n
+
+        # Covariance and variance
+        cov = sum(
+            (t - mean_t) * (v - mean_v)
+            for t, v in zip(temperatures, voltages, strict=True)
+        )
+        var_t = sum((t - mean_t) ** 2 for t in temperatures)
+
+        if var_t == 0:
+            raise ValueError("Temperature variance is zero (all temps identical)")
+
+        slope = cov / var_t  # dV/dT in V/°C
+
+        # Find nominal voltage (voltage at median temperature)
+        sorted_pairs = sorted(zip(temperatures, voltages, strict=True))
+        mid_idx = len(sorted_pairs) // 2
+        v_nominal = sorted_pairs[mid_idx][1]
+
+        # Convert to ppm/°C: (dV/dT) / V_nom * 10^6
+        tempco_ppm = (slope / v_nominal) * 1e6
+
+        return tempco_ppm

tests/conftest.py

@@ -1 +1,8 @@
 """pytest fixtures for py_dvt_ate tests."""
+
+import pytest
+
+
+def pytest_configure(config: pytest.Config) -> None:
+    """Configure pytest markers."""
+    config.addinivalue_line("markers", "asyncio: mark test as async")

tests/integration/__init__.py

@@ -0,0 +1 @@
+"""Integration tests for py_dvt_ate."""

tests/integration/conftest.py

@@ -0,0 +1 @@
+"""Configuration for integration tests."""

tests/integration/test_tcp_server.py

@@ -0,0 +1,272 @@
+"""Integration tests for TCP server.
+
+Tests the InstrumentServer and SimulationServer with actual TCP connections.
+"""
+
+from __future__ import annotations
+
+import asyncio
+
+import pytest
+
+from py_dvt_ate.instruments.transport import InstrumentServer
+from py_dvt_ate.simulation.physics.engine import PhysicsEngine
+from py_dvt_ate.simulation.server import ServerConfig, SimulationServer
+from py_dvt_ate.simulation.virtual.chamber import ThermalChamberSim
+
+
+@pytest.mark.asyncio(loop_scope="function")
+class TestInstrumentServer:
+    """Tests for InstrumentServer TCP functionality."""
+
+    @pytest.fixture
+    def physics_engine(self) -> PhysicsEngine:
+        """Create a physics engine for testing."""
+        return PhysicsEngine(update_rate_hz=100.0)
+
+    @pytest.fixture
+    def server(self, physics_engine: PhysicsEngine) -> InstrumentServer:
+        """Create an instrument server with a thermal chamber."""
+        server = InstrumentServer(host="127.0.0.1")
+        chamber = ThermalChamberSim(physics_engine)
+        server.register_instrument(15000, chamber)
+        return server
+
+    async def test_server_start_stop(self, server: InstrumentServer) -> None:
+        """Test server can start and stop."""
+        assert not server.is_running
+
+        await server.start()
+        assert server.is_running
+
+        await server.stop()
+        assert not server.is_running
+
+    async def test_client_connection(self, server: InstrumentServer) -> None:
+        """Test client can connect and send command."""
+        await server.start()
+
+        try:
+            reader, writer = await asyncio.open_connection("127.0.0.1", 15000)
+
+            # Send *IDN? query
+            writer.write(b"*IDN?\n")
+            await writer.drain()
+
+            # Read response
+            response = await asyncio.wait_for(reader.readline(), timeout=2.0)
+            assert b"PyDVTATE" in response
+            assert b"TC-SIM-001" in response
+
+            writer.close()
+            await writer.wait_closed()
+        finally:
+            await server.stop()
+
+    async def test_multiple_commands(self, server: InstrumentServer) -> None:
+        """Test sending multiple commands in sequence."""
+        await server.start()
+
+        try:
+            reader, writer = await asyncio.open_connection("127.0.0.1", 15000)
+
+            # Set temperature setpoint
+            writer.write(b"TEMP:SETPOINT 85.0\n")
+            await writer.drain()
+
+            # Query setpoint
+            writer.write(b"TEMP:SETPOINT?\n")
+            await writer.drain()
+            response = await asyncio.wait_for(reader.readline(), timeout=2.0)
+            assert b"85.00" in response
+
+            # Query actual temperature
+            writer.write(b"TEMP:ACTUAL?\n")
+            await writer.drain()
+            response = await asyncio.wait_for(reader.readline(), timeout=2.0)
+            # Should return a valid float
+            temp = float(response.decode().strip())
+            assert -50 <= temp <= 200
+
+            writer.close()
+            await writer.wait_closed()
+        finally:
+            await server.stop()
+
+    async def test_concurrent_connections(
+        self, physics_engine: PhysicsEngine
+    ) -> None:
+        """Test multiple concurrent client connections."""
+        server = InstrumentServer(host="127.0.0.1")
+        chamber = ThermalChamberSim(physics_engine)
+        server.register_instrument(15001, chamber)
+
+        await server.start()
+
+        try:
+            # Connect two clients simultaneously
+            reader1, writer1 = await asyncio.open_connection("127.0.0.1", 15001)
+            reader2, writer2 = await asyncio.open_connection("127.0.0.1", 15001)
+
+            # Send command from client 1
+            writer1.write(b"*IDN?\n")
+            await writer1.drain()
+            response1 = await asyncio.wait_for(reader1.readline(), timeout=2.0)
+
+            # Send command from client 2
+            writer2.write(b"*IDN?\n")
+            await writer2.drain()
+            response2 = await asyncio.wait_for(reader2.readline(), timeout=2.0)
+
+            # Both should get valid responses
+            assert b"TC-SIM-001" in response1
+            assert b"TC-SIM-001" in response2
+
+            writer1.close()
+            writer2.close()
+            await writer1.wait_closed()
+            await writer2.wait_closed()
+        finally:
+            await server.stop()
+
+
+@pytest.mark.asyncio(loop_scope="function")
+class TestSimulationServer:
+    """Tests for complete SimulationServer."""
+
+    async def test_simulation_server_start_stop(self) -> None:
+        """Test simulation server lifecycle."""
+        config = ServerConfig(
+            host="127.0.0.1",
+            chamber_port=16000,
+            psu_port=16001,
+            dmm_port=16002,
+            physics_rate_hz=100.0,
+        )
+        server = SimulationServer(config)
+
+        assert not server.is_running
+
+        await server.start()
+        assert server.is_running
+        assert server.physics_engine is not None
+
+        await server.stop()
+        assert not server.is_running
+
+    async def test_all_instruments_accessible(self) -> None:
+        """Test all three instruments are accessible over TCP."""
+        config = ServerConfig(
+            host="127.0.0.1",
+            chamber_port=16100,
+            psu_port=16101,
+            dmm_port=16102,
+        )
+        server = SimulationServer(config)
+        await server.start()
+
+        try:
+            # Test thermal chamber
+            r, w = await asyncio.open_connection("127.0.0.1", 16100)
+            w.write(b"*IDN?\n")
+            await w.drain()
+            resp = await asyncio.wait_for(r.readline(), timeout=2.0)
+            assert b"TC-SIM-001" in resp
+            w.close()
+            await w.wait_closed()
+
+            # Test power supply
+            r, w = await asyncio.open_connection("127.0.0.1", 16101)
+            w.write(b"*IDN?\n")
+            await w.drain()
+            resp = await asyncio.wait_for(r.readline(), timeout=2.0)
+            assert b"PS-SIM-001" in resp
+            w.close()
+            await w.wait_closed()
+
+            # Test multimeter
+            r, w = await asyncio.open_connection("127.0.0.1", 16102)
+            w.write(b"*IDN?\n")
+            await w.drain()
+            resp = await asyncio.wait_for(r.readline(), timeout=2.0)
+            assert b"DMM-SIM-001" in resp
+            w.close()
+            await w.wait_closed()
+
+        finally:
+            await server.stop()
+
+    async def test_physics_engine_integration(self) -> None:
+        """Test instruments share physics engine state."""
+        config = ServerConfig(
+            host="127.0.0.1",
+            chamber_port=16200,
+            psu_port=16201,
+            dmm_port=16202,
+        )
+        server = SimulationServer(config)
+        await server.start()
+
+        try:
+            # Connect to power supply and enable output
+            psu_r, psu_w = await asyncio.open_connection("127.0.0.1", 16201)
+            psu_w.write(b"VOLT 5.0\n")
+            await psu_w.drain()
+            psu_w.write(b"OUTP ON\n")
+            await psu_w.drain()
+
+            # Run a few physics steps
+            await asyncio.sleep(0.1)
+
+            # Query voltage from power supply
+            psu_w.write(b"MEAS:VOLT?\n")
+            await psu_w.drain()
+            psu_resp = await asyncio.wait_for(psu_r.readline(), timeout=2.0)
+            psu_voltage = float(psu_resp.decode().strip())
+
+            # Connect to DMM and measure DUT output
+            dmm_r, dmm_w = await asyncio.open_connection("127.0.0.1", 16202)
+            dmm_w.write(b"MEAS:VOLT:DC?\n")
+            await dmm_w.drain()
+            dmm_resp = await asyncio.wait_for(dmm_r.readline(), timeout=2.0)
+            dmm_voltage = float(dmm_resp.decode().strip())
+
+            # PSU should show input voltage (5V)
+            assert 4.9 <= psu_voltage <= 5.1
+
+            # DMM should show DUT output voltage (LDO regulated ~3.3V)
+            assert 3.0 <= dmm_voltage <= 3.5
+
+            psu_w.close()
+            dmm_w.close()
+            await psu_w.wait_closed()
+            await dmm_w.wait_closed()
+
+        finally:
+            await server.stop()
+
+    async def test_error_handling(self) -> None:
+        """Test invalid commands return errors."""
+        config = ServerConfig(
+            host="127.0.0.1",
+            chamber_port=16300,
+            psu_port=16301,
+            dmm_port=16302,
+        )
+        server = SimulationServer(config)
+        await server.start()
+
+        try:
+            r, w = await asyncio.open_connection("127.0.0.1", 16300)
+
+            # Send invalid command
+            w.write(b"INVALID:COMMAND\n")
+            await w.drain()
+            resp = await asyncio.wait_for(r.readline(), timeout=2.0)
+            assert b"ERROR" in resp
+
+            w.close()
+            await w.wait_closed()
+
+        finally:
+            await server.stop()

tests/integration/test_tempco.py

@@ -0,0 +1,267 @@
+"""Integration tests for TempCo characterisation test.
+
+Full end-to-end test of the TempCo test with simulated instruments.
+"""
+
+from __future__ import annotations
+
+from pathlib import Path
+
+import pytest
+
+from py_dvt_ate.data.models import TestStatus
+from py_dvt_ate.data.repository import SQLiteRepository
+from py_dvt_ate.framework.context import TestContext
+from py_dvt_ate.framework.logger import TestLogger
+from py_dvt_ate.instruments.factory import InstrumentConfig, InstrumentFactory
+from py_dvt_ate.simulation.server import ServerConfig, SimulationServer
+from py_dvt_ate.tests.thermal.tempco import TempCoTest
+
+
+@pytest.mark.asyncio(loop_scope="function")
+class TestTempCoIntegration:
+    """Integration tests for TempCo test with simulator."""
+
+    async def test_tempco_runs_successfully(self, tmp_path: Path) -> None:
+        """Test TempCo test runs end-to-end with simulator."""
+        # Start simulation server
+        server_config = ServerConfig(
+            host="127.0.0.1",
+            chamber_port=17000,
+            psu_port=17001,
+            dmm_port=17002,
+            physics_rate_hz=100.0,
+        )
+        server = SimulationServer(server_config)
+        await server.start()
+
+        try:
+            # Create instrument set connected to simulator
+            instrument_config = InstrumentConfig(
+                backend="simulator",
+                simulator_host="127.0.0.1",
+                chamber_port=17000,
+                psu_port=17001,
+                dmm_port=17002,
+            )
+            instruments = InstrumentFactory.create(instrument_config)
+
+            # Connect to instruments
+            instruments.chamber.connect()
+            instruments.psu.connect()
+            instruments.dmm.connect()
+
+            # Configure instruments
+            instruments.chamber.set_ramp_rate(10.0)  # Fast ramp for testing
+            instruments.psu.enable_output(1, False)  # Ensure off initially
+
+            # Create test repository
+            db_path = tmp_path / "test.db"
+            repository = SQLiteRepository(db_path)
+
+            # Create test run
+            run_id = repository.create_run(
+                test_name="tempco",
+                config={
+                    "temperatures": [0.0, 25.0, 50.0],  # Reduced for faster test
+                    "input_voltage": 5.0,
+                    "load_current": 0.1,
+                    "settle_time": 0.5,  # Reduced for faster test
+                    "num_samples": 3,  # Reduced for faster test
+                    "tempco_limit": 100.0,  # Relaxed for testing
+                },
+                description="Integration test of TempCo",
+            )
+
+            # Create test logger
+            logger = TestLogger(run_id, repository)
+
+            # Create test context
+            context = TestContext(
+                run_id=run_id,
+                instruments=instruments,
+                logger=logger,
+                config={
+                    "temperatures": [0.0, 25.0, 50.0],
+                    "input_voltage": 5.0,
+                    "load_current": 0.1,
+                    "settle_time": 0.5,
+                    "num_samples": 3,
+                    "tempco_limit": 100.0,
+                },
+            )
+
+            # Create and execute test
+            test = TempCoTest()
+            assert test.name == "tempco"
+            assert test.description == "Output voltage temperature coefficient"
+
+            # Run test (this is synchronous, but simulation runs async in background)
+            status = test.execute(context)
+
+            # Verify test completed
+            assert status in (TestStatus.PASSED, TestStatus.FAILED)
+
+            # Flush logger to ensure all data is written
+            logger.flush()
+
+            # Update run status
+            repository.complete_run(run_id, status)
+
+            # Verify results were logged
+            results = repository.get_results(run_id)
+            assert len(results) > 0
+
+            # Find TempCo result
+            tempco_result = next(r for r in results if r.parameter == "temp_co")
+            assert tempco_result is not None
+            assert tempco_result.unit == "ppm/°C"
+            assert tempco_result.lower_limit == -100.0
+            assert tempco_result.upper_limit == 100.0
+
+            # Verify measurements were logged
+            df = repository.get_measurements_dataframe(run_id)
+            assert df is not None
+            assert len(df) >= 3  # At least 3 temperature points
+
+            # Verify v_out measurements exist
+            vout_measurements = df[df["parameter"] == "v_out"]
+            assert len(vout_measurements) >= 3
+
+            # Verify temperature conditions were logged
+            assert "temperature" in df.columns
+            temps_recorded = vout_measurements["temperature"].unique()
+            assert len(temps_recorded) >= 3
+
+        finally:
+            await server.stop()
+
+    async def test_tempco_with_minimal_config(self, tmp_path: Path) -> None:
+        """Test TempCo uses default configuration when not specified."""
+        # Start simulation server
+        server_config = ServerConfig(
+            host="127.0.0.1",
+            chamber_port=17100,
+            psu_port=17101,
+            dmm_port=17102,
+        )
+        server = SimulationServer(server_config)
+        await server.start()
+
+        try:
+            # Create instrument set
+            instrument_config = InstrumentConfig(
+                backend="simulator",
+                simulator_host="127.0.0.1",
+                chamber_port=17100,
+                psu_port=17101,
+                dmm_port=17102,
+            )
+            instruments = InstrumentFactory.create(instrument_config)
+
+            # Connect to instruments
+            instruments.chamber.connect()
+            instruments.psu.connect()
+            instruments.dmm.connect()
+
+            # Create repository
+            db_path = tmp_path / "test_minimal.db"
+            repository = SQLiteRepository(db_path)
+            run_id = repository.create_run(
+                test_name="tempco",
+                config={},  # Empty config - should use defaults
+            )
+
+            # Create logger and context with minimal config
+            logger = TestLogger(run_id, repository)
+            context = TestContext(
+                run_id=run_id,
+                instruments=instruments,
+                logger=logger,
+                config={
+                    # Override temperatures for faster test
+                    "temperatures": [25.0, 50.0],
+                    "settle_time": 0.2,
+                    "num_samples": 2,
+                },
+            )
+
+            # Execute test
+            test = TempCoTest()
+            status = test.execute(context)
+
+            # Should complete without error
+            assert status in (TestStatus.PASSED, TestStatus.FAILED, TestStatus.ERROR)
+
+            logger.flush()
+            repository.complete_run(run_id, status)
+
+            # Verify some data was logged
+            results = repository.get_results(run_id)
+            assert len(results) >= 1
+
+        finally:
+            await server.stop()
+
+    async def test_tempco_handles_errors_gracefully(self, tmp_path: Path) -> None:
+        """Test TempCo returns ERROR status when instruments fail."""
+        # Start simulation server
+        server_config = ServerConfig(
+            host="127.0.0.1",
+            chamber_port=17200,
+            psu_port=17201,
+            dmm_port=17202,
+        )
+        server = SimulationServer(server_config)
+        await server.start()
+
+        try:
+            # Create instrument set
+            instrument_config = InstrumentConfig(
+                backend="simulator",
+                simulator_host="127.0.0.1",
+                chamber_port=17200,
+                psu_port=17201,
+                dmm_port=17202,
+            )
+            instruments = InstrumentFactory.create(instrument_config)
+
+            # Connect to instruments
+            instruments.chamber.connect()
+            instruments.psu.connect()
+            instruments.dmm.connect()
+
+            # Create repository
+            db_path = tmp_path / "test_error.db"
+            repository = SQLiteRepository(db_path)
+            run_id = repository.create_run(test_name="tempco", config={})
+
+            # Create logger and context
+            logger = TestLogger(run_id, repository)
+            context = TestContext(
+                run_id=run_id,
+                instruments=instruments,
+                logger=logger,
+                config={
+                    "temperatures": [],  # Invalid: empty temperature list
+                    "settle_time": 0.1,
+                },
+            )
+
+            # Execute test
+            test = TempCoTest()
+
+            # Should handle gracefully (may return FAILED or ERROR)
+            # The test should not raise an unhandled exception
+            try:
+                status = test.execute(context)
+                # If it completes, it should indicate an error or failure
+                assert status in (TestStatus.ERROR, TestStatus.FAILED)
+            except Exception:
+                # Or it might raise, which we also consider handled
+                pass
+
+            logger.flush()
+
+        finally:
+            await server.stop()

tests/unit/test_config.py

@@ -0,0 +1,266 @@
+"""Tests for configuration loading and validation."""
+
+from pathlib import Path
+from typing import Any
+
+import pytest
+import yaml
+from pydantic import ValidationError
+
+from py_dvt_ate.app.config import (
+    APIConfig,
+    AppConfig,
+    ChamberConfig,
+    DashboardConfig,
+    DataConfig,
+    DUTConfig,
+    DUTParameters,
+    InstrumentsConfig,
+    LoggingConfig,
+    PhysicsConfig,
+    PyVISAConfig,
+    SimulatorConfig,
+    ThermalConfig,
+    load_config,
+)
+
+
+def test_default_config_values() -> None:
+    """Test that default configuration values are correct."""
+    config = AppConfig()
+
+    assert config.instruments.backend == "simulator"
+    assert config.instruments.simulator.host == "localhost"
+    assert config.instruments.simulator.thermal_chamber_port == 5001
+
+    assert config.physics.update_rate_hz == 100.0
+    assert config.physics.thermal.chamber_time_constant_s == 30.0
+    assert config.physics.thermal.theta_jc == 15.0
+
+    assert config.dut.model == "ldo"
+    assert config.dut.parameters.nominal_output_voltage == 3.3
+    assert config.dut.parameters.tempco_ppm_per_c == 50.0
+
+    assert config.data.database_path == "./data/py_dvt_ate.db"
+    assert config.logging.level == "INFO"
+    assert config.dashboard.enabled is True
+    assert config.api.enabled is False
+
+
+def test_load_config_with_defaults_only() -> None:
+    """Test loading config without a file uses defaults."""
+    config = load_config(None)
+
+    assert config.instruments.backend == "simulator"
+    assert config.physics.update_rate_hz == 100.0
+
+
+def test_load_config_from_file(tmp_path: Path) -> None:
+    """Test loading configuration from YAML file."""
+    config_file = tmp_path / "test_config.yaml"
+    config_data = {
+        "instruments": {"backend": "pyvisa"},
+        "physics": {"update_rate_hz": 50.0},
+        "dut": {"model": "custom_ldo"},
+    }
+
+    with config_file.open("w") as f:
+        yaml.dump(config_data, f)
+
+    config = load_config(config_file)
+
+    assert config.instruments.backend == "pyvisa"
+    assert config.physics.update_rate_hz == 50.0
+    assert config.dut.model == "custom_ldo"
+    # Defaults still apply
+    assert config.instruments.simulator.host == "localhost"
+
+
+def test_load_config_partial_override(tmp_path: Path) -> None:
+    """Test that partial config overrides work correctly."""
+    config_file = tmp_path / "partial.yaml"
+    config_data = {
+        "physics": {
+            "thermal": {
+                "theta_jc": 20.0,
+                # Other thermal params should use defaults
+            }
+        }
+    }
+
+    with config_file.open("w") as f:
+        yaml.dump(config_data, f)
+
+    config = load_config(config_file)
+
+    # Overridden value
+    assert config.physics.thermal.theta_jc == 20.0
+    # Default values
+    assert config.physics.thermal.theta_ca == 5.0
+    assert config.physics.thermal.chamber_time_constant_s == 30.0
+
+
+def test_load_config_missing_file() -> None:
+    """Test that loading from missing file raises FileNotFoundError."""
+    with pytest.raises(FileNotFoundError, match="Configuration file not found"):
+        load_config("nonexistent.yaml")
+
+
+def test_load_config_invalid_yaml(tmp_path: Path) -> None:
+    """Test that malformed YAML raises an error."""
+    config_file = tmp_path / "invalid.yaml"
+    config_file.write_text("invalid: yaml: content: [\n")
+
+    with pytest.raises(yaml.YAMLError):
+        load_config(config_file)
+
+
+def test_load_config_validation_error(tmp_path: Path) -> None:
+    """Test that invalid configuration raises ValidationError."""
+    config_file = tmp_path / "invalid_config.yaml"
+    config_data = {
+        "instruments": {"backend": "invalid_backend"},  # Not in Literal["simulator", "pyvisa"]
+    }
+
+    with config_file.open("w") as f:
+        yaml.dump(config_data, f)
+
+    with pytest.raises(ValidationError):
+        load_config(config_file)
+
+
+def test_env_override_simple(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+    """Test environment variable override for simple values."""
+    config_file = tmp_path / "config.yaml"
+    config_data: dict[str, Any] = {}
+
+    with config_file.open("w") as f:
+        yaml.dump(config_data, f)
+
+    monkeypatch.setenv("PYDVTATE__INSTRUMENTS__BACKEND", "pyvisa")
+    monkeypatch.setenv("PYDVTATE__PHYSICS__UPDATE_RATE_HZ", "200.0")
+
+    config = load_config(config_file)
+
+    assert config.instruments.backend == "pyvisa"
+    assert config.physics.update_rate_hz == 200.0
+
+
+def test_env_override_nested(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+    """Test environment variable override for nested values."""
+    config_file = tmp_path / "config.yaml"
+    config_data: dict[str, Any] = {}
+
+    with config_file.open("w") as f:
+        yaml.dump(config_data, f)
+
+    monkeypatch.setenv("PYDVTATE__INSTRUMENTS__SIMULATOR__HOST", "192.168.1.100")
+    monkeypatch.setenv("PYDVTATE__INSTRUMENTS__SIMULATOR__THERMAL_CHAMBER_PORT", "6001")
+    monkeypatch.setenv("PYDVTATE__PHYSICS__THERMAL__THETA_JC", "25.0")
+
+    config = load_config(config_file)
+
+    assert config.instruments.simulator.host == "192.168.1.100"
+    assert config.instruments.simulator.thermal_chamber_port == 6001
+    assert config.physics.thermal.theta_jc == 25.0
+
+
+def test_env_override_types(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+    """Test that environment variables are parsed to correct types."""
+    config_file = tmp_path / "config.yaml"
+    config_data: dict[str, Any] = {}
+
+    with config_file.open("w") as f:
+        yaml.dump(config_data, f)
+
+    monkeypatch.setenv("PYDVTATE__DASHBOARD__ENABLED", "false")  # bool
+    monkeypatch.setenv("PYDVTATE__DASHBOARD__PORT", "9000")  # int
+    monkeypatch.setenv("PYDVTATE__PHYSICS__UPDATE_RATE_HZ", "75.5")  # float
+
+    config = load_config(config_file)
+
+    assert config.dashboard.enabled is False
+    assert config.dashboard.port == 9000
+    assert config.physics.update_rate_hz == 75.5
+
+
+def test_env_override_precedence(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
+    """Test that environment variables override file values."""
+    config_file = tmp_path / "config.yaml"
+    config_data = {"physics": {"update_rate_hz": 50.0}}
+
+    with config_file.open("w") as f:
+        yaml.dump(config_data, f)
+
+    monkeypatch.setenv("PYDVTATE__PHYSICS__UPDATE_RATE_HZ", "150.0")
+
+    config = load_config(config_file)
+
+    # Environment variable should win
+    assert config.physics.update_rate_hz == 150.0
+
+
+def test_env_variables_ignored_without_prefix(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    """Test that environment variables without prefix are ignored."""
+    config_file = tmp_path / "config.yaml"
+    config_data: dict[str, Any] = {}
+
+    with config_file.open("w") as f:
+        yaml.dump(config_data, f)
+
+    # These should be ignored
+    monkeypatch.setenv("BACKEND", "pyvisa")
+    monkeypatch.setenv("UPDATE_RATE_HZ", "200.0")
+
+    config = load_config(config_file)
+
+    # Should use defaults
+    assert config.instruments.backend == "simulator"
+    assert config.physics.update_rate_hz == 100.0
+
+
+def test_simulator_config_defaults() -> None:
+    """Test SimulatorConfig default values."""
+    config = SimulatorConfig()
+    assert config.host == "localhost"
+    assert config.thermal_chamber_port == 5001
+    assert config.power_supply_port == 5002
+    assert config.multimeter_port == 5003
+
+
+def test_pyvisa_config_defaults() -> None:
+    """Test PyVISAConfig default values."""
+    config = PyVISAConfig()
+    assert config.thermal_chamber is None
+    assert config.power_supply is None
+    assert config.multimeter is None
+
+
+def test_complete_config_structure() -> None:
+    """Test that all config sections can be instantiated."""
+    config = AppConfig(
+        instruments=InstrumentsConfig(
+            backend="pyvisa",
+            simulator=SimulatorConfig(host="192.168.1.1"),
+            pyvisa=PyVISAConfig(thermal_chamber="TCPIP::192.168.1.10::INSTR"),
+        ),
+        physics=PhysicsConfig(
+            update_rate_hz=50.0,
+            thermal=ThermalConfig(theta_jc=20.0),
+            chamber=ChamberConfig(ramp_rate_c_per_min=5.0),
+        ),
+        dut=DUTConfig(
+            model="custom", parameters=DUTParameters(nominal_output_voltage=5.0)
+        ),
+        data=DataConfig(database_path="/tmp/test.db"),
+        logging=LoggingConfig(level="DEBUG"),
+        dashboard=DashboardConfig(enabled=False),
+        api=APIConfig(enabled=True, port=9000),
+    )
+
+    assert config.instruments.backend == "pyvisa"
+    assert config.physics.update_rate_hz == 50.0
+    assert config.dut.parameters.nominal_output_voltage == 5.0
+    assert config.api.port == 9000

tests/unit/test_drivers.py

@@ -0,0 +1,346 @@
+"""Unit tests for instrument drivers.
+
+Tests SCPI command formatting and driver functionality using mock transports.
+"""
+
+from unittest.mock import MagicMock
+
+import pytest
+
+from py_dvt_ate.instruments.drivers.base import BaseDriver
+from py_dvt_ate.instruments.drivers.chamber import ThermalChamberDriver
+from py_dvt_ate.instruments.drivers.multimeter import MultimeterDriver
+from py_dvt_ate.instruments.drivers.power_supply import PowerSupplyDriver
+
+
+@pytest.fixture
+def mock_transport():
+    """Create a mock transport for testing."""
+    transport = MagicMock()
+    transport.is_connected = True
+    return transport
+
+
+class TestBaseDriver:
+    """Tests for BaseDriver base class."""
+
+    def test_connect(self, mock_transport):
+        """Test connection establishment."""
+        driver = BaseDriver(mock_transport)
+        driver.connect()
+        mock_transport.connect.assert_called_once()
+
+    def test_disconnect(self, mock_transport):
+        """Test disconnection."""
+        driver = BaseDriver(mock_transport)
+        driver.disconnect()
+        mock_transport.disconnect.assert_called_once()
+
+    def test_is_connected(self, mock_transport):
+        """Test connection status check."""
+        driver = BaseDriver(mock_transport)
+        assert driver.is_connected is True
+
+    def test_write(self, mock_transport):
+        """Test SCPI command write."""
+        driver = BaseDriver(mock_transport)
+        driver.write("VOLT 3.3")
+        mock_transport.write.assert_called_once_with("VOLT 3.3")
+
+    def test_query(self, mock_transport):
+        """Test SCPI query."""
+        mock_transport.query.return_value = "3.300"
+        driver = BaseDriver(mock_transport)
+        result = driver.query("VOLT?")
+        assert result == "3.300"
+        mock_transport.query.assert_called_once_with("VOLT?", None)
+
+    def test_query_float(self, mock_transport):
+        """Test SCPI query with float parsing."""
+        mock_transport.query.return_value = "3.300"
+        driver = BaseDriver(mock_transport)
+        result = driver.query_float("VOLT?")
+        assert result == 3.3
+        assert isinstance(result, float)
+
+    def test_query_float_invalid(self, mock_transport):
+        """Test SCPI query with invalid float response."""
+        mock_transport.query.return_value = "INVALID"
+        driver = BaseDriver(mock_transport)
+        with pytest.raises(ValueError, match="Cannot parse 'INVALID' as float"):
+            driver.query_float("VOLT?")
+
+    def test_query_int(self, mock_transport):
+        """Test SCPI query with integer parsing."""
+        mock_transport.query.return_value = "42"
+        driver = BaseDriver(mock_transport)
+        result = driver.query_int("COUNT?")
+        assert result == 42
+        assert isinstance(result, int)
+
+    def test_query_int_invalid(self, mock_transport):
+        """Test SCPI query with invalid integer response."""
+        mock_transport.query.return_value = "3.14"
+        driver = BaseDriver(mock_transport)
+        with pytest.raises(ValueError, match="Cannot parse '3.14' as int"):
+            driver.query_int("COUNT?")
+
+    def test_query_bool_true_variants(self, mock_transport):
+        """Test SCPI query with boolean parsing - true variants."""
+        driver = BaseDriver(mock_transport)
+
+        for value in ["1", "ON", "TRUE", "on", "true"]:
+            mock_transport.query.return_value = value
+            result = driver.query_bool("OUTP?")
+            assert result is True
+
+    def test_query_bool_false_variants(self, mock_transport):
+        """Test SCPI query with boolean parsing - false variants."""
+        driver = BaseDriver(mock_transport)
+
+        for value in ["0", "OFF", "FALSE", "off", "false"]:
+            mock_transport.query.return_value = value
+            result = driver.query_bool("OUTP?")
+            assert result is False
+
+    def test_query_bool_invalid(self, mock_transport):
+        """Test SCPI query with invalid boolean response."""
+        mock_transport.query.return_value = "MAYBE"
+        driver = BaseDriver(mock_transport)
+        with pytest.raises(ValueError, match="Cannot parse 'MAYBE' as bool"):
+            driver.query_bool("OUTP?")
+
+    def test_identify(self, mock_transport):
+        """Test instrument identification query."""
+        mock_transport.query.return_value = "Manufacturer,Model,SN123,1.0.0"
+        driver = BaseDriver(mock_transport)
+        result = driver.identify()
+        assert result == "Manufacturer,Model,SN123,1.0.0"
+        mock_transport.query.assert_called_once_with("*IDN?", None)
+
+    def test_reset(self, mock_transport):
+        """Test instrument reset command."""
+        driver = BaseDriver(mock_transport)
+        driver.reset()
+        mock_transport.write.assert_called_once_with("*RST")
+
+    def test_clear_status(self, mock_transport):
+        """Test clear status command."""
+        driver = BaseDriver(mock_transport)
+        driver.clear_status()
+        mock_transport.write.assert_called_once_with("*CLS")
+
+    def test_operation_complete(self, mock_transport):
+        """Test operation complete query."""
+        mock_transport.query.return_value = "1"
+        driver = BaseDriver(mock_transport)
+        result = driver.operation_complete()
+        assert result is True
+        mock_transport.query.assert_called_once_with("*OPC?", None)
+
+
+class TestThermalChamberDriver:
+    """Tests for ThermalChamberDriver."""
+
+    def test_set_temperature(self, mock_transport):
+        """Test temperature setpoint command."""
+        driver = ThermalChamberDriver(mock_transport)
+        driver.set_temperature(85.0)
+        mock_transport.write.assert_called_once_with("TEMP:SETPOINT 85.00")
+
+    def test_get_temperature(self, mock_transport):
+        """Test temperature measurement query."""
+        mock_transport.query.return_value = "25.50"
+        driver = ThermalChamberDriver(mock_transport)
+        temp = driver.get_temperature()
+        assert temp == 25.5
+        mock_transport.query.assert_called_once_with("TEMP:ACTUAL?", None)
+
+    def test_get_setpoint(self, mock_transport):
+        """Test setpoint query."""
+        mock_transport.query.return_value = "85.00"
+        driver = ThermalChamberDriver(mock_transport)
+        setpoint = driver.get_setpoint()
+        assert setpoint == 85.0
+        mock_transport.query.assert_called_once_with("TEMP:SETPOINT?", None)
+
+    def test_is_stable_true(self, mock_transport):
+        """Test stability check - stable."""
+        mock_transport.query.return_value = "1"
+        driver = ThermalChamberDriver(mock_transport)
+        assert driver.is_stable() is True
+
+    def test_is_stable_false(self, mock_transport):
+        """Test stability check - not stable."""
+        mock_transport.query.return_value = "0"
+        driver = ThermalChamberDriver(mock_transport)
+        assert driver.is_stable() is False
+
+    def test_wait_until_stable_immediate(self, mock_transport):
+        """Test wait for stability - already stable."""
+        mock_transport.query.return_value = "1"
+        driver = ThermalChamberDriver(mock_transport)
+        result = driver.wait_until_stable(timeout=5.0, poll_interval=0.1)
+        assert result is True
+
+    def test_wait_until_stable_timeout(self, mock_transport):
+        """Test wait for stability - timeout."""
+        mock_transport.query.return_value = "0"  # Never becomes stable
+        driver = ThermalChamberDriver(mock_transport)
+        result = driver.wait_until_stable(timeout=0.2, poll_interval=0.1)
+        assert result is False
+
+    def test_wait_until_stable_invalid_timeout(self, mock_transport):
+        """Test wait with negative timeout."""
+        driver = ThermalChamberDriver(mock_transport)
+        with pytest.raises(ValueError, match="Timeout must be non-negative"):
+            driver.wait_until_stable(timeout=-1.0)
+
+    def test_wait_until_stable_invalid_interval(self, mock_transport):
+        """Test wait with non-positive poll interval."""
+        driver = ThermalChamberDriver(mock_transport)
+        with pytest.raises(ValueError, match="Poll interval must be positive"):
+            driver.wait_until_stable(poll_interval=0.0)
+
+    def test_set_ramp_rate(self, mock_transport):
+        """Test ramp rate command."""
+        driver = ThermalChamberDriver(mock_transport)
+        driver.set_ramp_rate(5.0)
+        mock_transport.write.assert_called_once_with("TEMP:RAMP 5.00")
+
+    def test_get_ramp_rate(self, mock_transport):
+        """Test ramp rate query."""
+        mock_transport.query.return_value = "5.00"
+        driver = ThermalChamberDriver(mock_transport)
+        rate = driver.get_ramp_rate()
+        assert rate == 5.0
+
+
+class TestPowerSupplyDriver:
+    """Tests for PowerSupplyDriver."""
+
+    def test_set_voltage(self, mock_transport):
+        """Test voltage setpoint command."""
+        driver = PowerSupplyDriver(mock_transport)
+        driver.set_voltage(1, 3.3)
+        mock_transport.write.assert_called_once_with("VOLT 3.300")
+
+    def test_get_voltage(self, mock_transport):
+        """Test voltage setpoint query."""
+        mock_transport.query.return_value = "3.300"
+        driver = PowerSupplyDriver(mock_transport)
+        voltage = driver.get_voltage(1)
+        assert voltage == 3.3
+
+    def test_set_current_limit(self, mock_transport):
+        """Test current limit command."""
+        driver = PowerSupplyDriver(mock_transport)
+        driver.set_current_limit(1, 0.5)
+        mock_transport.write.assert_called_once_with("CURR 0.500")
+
+    def test_get_current_limit(self, mock_transport):
+        """Test current limit query."""
+        mock_transport.query.return_value = "0.500"
+        driver = PowerSupplyDriver(mock_transport)
+        current = driver.get_current_limit(1)
+        assert current == 0.5
+
+    def test_measure_voltage(self, mock_transport):
+        """Test voltage measurement."""
+        mock_transport.query.return_value = "3.305"
+        driver = PowerSupplyDriver(mock_transport)
+        voltage = driver.measure_voltage(1)
+        assert voltage == 3.305
+        mock_transport.query.assert_called_once_with("MEAS:VOLT?", None)
+
+    def test_measure_current(self, mock_transport):
+        """Test current measurement."""
+        mock_transport.query.return_value = "0.125"
+        driver = PowerSupplyDriver(mock_transport)
+        current = driver.measure_current(1)
+        assert current == 0.125
+        mock_transport.query.assert_called_once_with("MEAS:CURR?", None)
+
+    def test_enable_output_on(self, mock_transport):
+        """Test enable output command."""
+        driver = PowerSupplyDriver(mock_transport)
+        driver.enable_output(1, True)
+        mock_transport.write.assert_called_once_with("OUTP ON")
+
+    def test_enable_output_off(self, mock_transport):
+        """Test disable output command."""
+        driver = PowerSupplyDriver(mock_transport)
+        driver.enable_output(1, False)
+        mock_transport.write.assert_called_once_with("OUTP OFF")
+
+    def test_is_output_enabled_true(self, mock_transport):
+        """Test output enabled query - enabled."""
+        mock_transport.query.return_value = "1"
+        driver = PowerSupplyDriver(mock_transport)
+        assert driver.is_output_enabled(1) is True
+
+    def test_is_output_enabled_false(self, mock_transport):
+        """Test output enabled query - disabled."""
+        mock_transport.query.return_value = "0"
+        driver = PowerSupplyDriver(mock_transport)
+        assert driver.is_output_enabled(1) is False
+
+
+class TestMultimeterDriver:
+    """Tests for MultimeterDriver."""
+
+    def test_measure_dc_voltage(self, mock_transport):
+        """Test DC voltage measurement."""
+        mock_transport.query.return_value = "3.300000"
+        driver = MultimeterDriver(mock_transport)
+        voltage = driver.measure_dc_voltage()
+        assert voltage == 3.3
+        mock_transport.query.assert_called_once_with("MEAS:VOLT:DC?", None)
+
+    def test_measure_dc_current(self, mock_transport):
+        """Test DC current measurement."""
+        mock_transport.query.return_value = "0.125000"
+        driver = MultimeterDriver(mock_transport)
+        current = driver.measure_dc_current()
+        assert current == 0.125
+        mock_transport.query.assert_called_once_with("MEAS:CURR:DC?", None)
+
+    def test_measure_resistance_not_implemented(self, mock_transport):
+        """Test resistance measurement raises NotImplementedError."""
+        driver = MultimeterDriver(mock_transport)
+        with pytest.raises(NotImplementedError, match="Resistance measurement"):
+            driver.measure_resistance()
+
+    def test_set_integration_time_not_implemented(self, mock_transport):
+        """Test integration time setting raises NotImplementedError."""
+        driver = MultimeterDriver(mock_transport)
+        with pytest.raises(NotImplementedError, match="Integration time"):
+            driver.set_integration_time(1.0)
+
+    def test_configure_dc_voltage(self, mock_transport):
+        """Test configure for DC voltage."""
+        driver = MultimeterDriver(mock_transport)
+        driver.configure_dc_voltage()
+        mock_transport.write.assert_called_once_with("CONF:VOLT:DC")
+
+    def test_configure_dc_current(self, mock_transport):
+        """Test configure for DC current."""
+        driver = MultimeterDriver(mock_transport)
+        driver.configure_dc_current()
+        mock_transport.write.assert_called_once_with("CONF:CURR:DC")
+
+    def test_get_configuration(self, mock_transport):
+        """Test get current configuration."""
+        mock_transport.query.return_value = '"VOLT:DC"'
+        driver = MultimeterDriver(mock_transport)
+        config = driver.get_configuration()
+        assert config == "VOLT:DC"
+        mock_transport.query.assert_called_once_with("CONF?", None)
+
+    def test_read(self, mock_transport):
+        """Test read measurement with current configuration."""
+        mock_transport.query.return_value = "3.300000"
+        driver = MultimeterDriver(mock_transport)
+        value = driver.read()
+        assert value == 3.3
+        mock_transport.query.assert_called_once_with("READ?", None)

tests/unit/test_instruments.py

@@ -0,0 +1,273 @@
+"""Unit tests for instrument interfaces and factory.
+
+Tests the Hardware Abstraction Layer (HAL) interfaces and the factory
+pattern for creating instrument sets.
+"""
+
+import pytest
+
+from py_dvt_ate.instruments import (
+    IMultimeter,
+    IPowerSupply,
+    IThermalChamber,
+    InstrumentConfig,
+    InstrumentFactory,
+    InstrumentSet,
+)
+from py_dvt_ate.instruments.drivers import (
+    MultimeterDriver,
+    PowerSupplyDriver,
+    ThermalChamberDriver,
+)
+
+
+class TestInterfaceImplementation:
+    """Test that drivers correctly implement the interface protocols."""
+
+    def test_thermal_chamber_implements_interface(self):
+        """Verify ThermalChamberDriver implements IThermalChamber."""
+        # ABC inheritance ensures interface compliance at class definition time
+        assert issubclass(ThermalChamberDriver, IThermalChamber)
+
+    def test_power_supply_implements_interface(self):
+        """Verify PowerSupplyDriver implements IPowerSupply."""
+        assert issubclass(PowerSupplyDriver, IPowerSupply)
+
+    def test_multimeter_implements_interface(self):
+        """Verify MultimeterDriver implements IMultimeter."""
+        assert issubclass(MultimeterDriver, IMultimeter)
+
+    def test_thermal_chamber_has_all_methods(self):
+        """Verify ThermalChamberDriver has all required methods."""
+        required_methods = [
+            "set_temperature",
+            "get_temperature",
+            "get_setpoint",
+            "is_stable",
+            "wait_until_stable",
+            "set_ramp_rate",
+        ]
+        for method in required_methods:
+            assert hasattr(ThermalChamberDriver, method)
+
+    def test_power_supply_has_all_methods(self):
+        """Verify PowerSupplyDriver has all required methods."""
+        required_methods = [
+            "set_voltage",
+            "get_voltage",
+            "set_current_limit",
+            "get_current_limit",
+            "measure_voltage",
+            "measure_current",
+            "enable_output",
+            "is_output_enabled",
+        ]
+        for method in required_methods:
+            assert hasattr(PowerSupplyDriver, method)
+
+    def test_multimeter_has_all_methods(self):
+        """Verify MultimeterDriver has all required methods."""
+        required_methods = [
+            "measure_dc_voltage",
+            "measure_dc_current",
+            "measure_resistance",
+            "set_integration_time",
+        ]
+        for method in required_methods:
+            assert hasattr(MultimeterDriver, method)
+
+
+class TestInstrumentSet:
+    """Test the InstrumentSet dataclass."""
+
+    def test_instrument_set_creation(self):
+        """Verify InstrumentSet can be created with mock instruments."""
+        from unittest.mock import Mock
+
+        # Create mock instruments that satisfy the interface
+        mock_chamber = Mock(spec=IThermalChamber)
+        mock_psu = Mock(spec=IPowerSupply)
+        mock_dmm = Mock(spec=IMultimeter)
+
+        instrument_set = InstrumentSet(
+            chamber=mock_chamber, psu=mock_psu, dmm=mock_dmm
+        )
+
+        assert instrument_set.chamber is mock_chamber
+        assert instrument_set.psu is mock_psu
+        assert instrument_set.dmm is mock_dmm
+
+    def test_instrument_set_type_annotations(self):
+        """Verify InstrumentSet has correct type annotations."""
+        annotations = InstrumentSet.__annotations__
+
+        assert annotations["chamber"] == IThermalChamber
+        assert annotations["psu"] == IPowerSupply
+        assert annotations["dmm"] == IMultimeter
+
+
+class TestInstrumentConfig:
+    """Test the InstrumentConfig dataclass."""
+
+    def test_config_defaults_simulator(self):
+        """Verify default configuration for simulator backend."""
+        config = InstrumentConfig(backend="simulator")
+
+        assert config.backend == "simulator"
+        assert config.simulator_host == "localhost"
+        assert config.chamber_port == 5001
+        assert config.psu_port == 5002
+        assert config.dmm_port == 5003
+        assert config.chamber_visa is None
+        assert config.psu_visa is None
+        assert config.dmm_visa is None
+
+    def test_config_custom_ports(self):
+        """Verify configuration accepts custom port settings."""
+        config = InstrumentConfig(
+            backend="simulator",
+            simulator_host="192.168.1.100",
+            chamber_port=6001,
+            psu_port=6002,
+            dmm_port=6003,
+        )
+
+        assert config.simulator_host == "192.168.1.100"
+        assert config.chamber_port == 6001
+        assert config.psu_port == 6002
+        assert config.dmm_port == 6003
+
+    def test_config_pyvisa_backend(self):
+        """Verify configuration for PyVISA backend."""
+        config = InstrumentConfig(
+            backend="pyvisa",
+            chamber_visa="TCPIP::192.168.1.10::INSTR",
+            psu_visa="TCPIP::192.168.1.11::INSTR",
+            dmm_visa="TCPIP::192.168.1.12::INSTR",
+        )
+
+        assert config.backend == "pyvisa"
+        assert config.chamber_visa == "TCPIP::192.168.1.10::INSTR"
+        assert config.psu_visa == "TCPIP::192.168.1.11::INSTR"
+        assert config.dmm_visa == "TCPIP::192.168.1.12::INSTR"
+
+
+class TestInstrumentFactory:
+    """Test the InstrumentFactory."""
+
+    def test_factory_rejects_unknown_backend(self):
+        """Verify factory raises error for unknown backend."""
+        config = InstrumentConfig(backend="invalid")  # type: ignore
+
+        with pytest.raises(ValueError, match="Unknown backend: invalid"):
+            InstrumentFactory.create(config)
+
+    def test_factory_pyvisa_not_implemented(self):
+        """Verify PyVISA backend raises NotImplementedError."""
+        config = InstrumentConfig(backend="pyvisa")
+
+        with pytest.raises(NotImplementedError, match="PyVISA backend not yet"):
+            InstrumentFactory.create(config)
+
+    def test_factory_creates_instrument_set(self):
+        """Verify factory creates InstrumentSet with correct structure."""
+        from unittest.mock import Mock, patch
+
+        config = InstrumentConfig(backend="simulator")
+
+        # Mock the transports and drivers to avoid actual connections
+        # Patch where they're imported FROM, not where they're used
+        with (
+            patch(
+                "py_dvt_ate.instruments.transport.tcp.TCPTransport"
+            ) as mock_tcp_transport,
+            patch(
+                "py_dvt_ate.instruments.drivers.chamber.ThermalChamberDriver"
+            ) as mock_chamber,
+            patch(
+                "py_dvt_ate.instruments.drivers.power_supply.PowerSupplyDriver"
+            ) as mock_psu,
+            patch(
+                "py_dvt_ate.instruments.drivers.multimeter.MultimeterDriver"
+            ) as mock_dmm,
+        ):
+            # Create mock instrument instances
+            mock_chamber_instance = Mock(spec=IThermalChamber)
+            mock_psu_instance = Mock(spec=IPowerSupply)
+            mock_dmm_instance = Mock(spec=IMultimeter)
+
+            mock_chamber.return_value = mock_chamber_instance
+            mock_psu.return_value = mock_psu_instance
+            mock_dmm.return_value = mock_dmm_instance
+
+            instrument_set = InstrumentFactory.create(config)
+
+            # Verify InstrumentSet was created
+            assert isinstance(instrument_set, InstrumentSet)
+
+            # Verify transports were created with correct parameters
+            assert mock_tcp_transport.call_count == 3
+            mock_tcp_transport.assert_any_call("localhost", 5001)  # chamber
+            mock_tcp_transport.assert_any_call("localhost", 5002)  # psu
+            mock_tcp_transport.assert_any_call("localhost", 5003)  # dmm
+
+            # Verify drivers were created
+            assert mock_chamber.call_count == 1
+            assert mock_psu.call_count == 1
+            assert mock_dmm.call_count == 1
+
+            # Verify InstrumentSet contains the mock instances
+            assert instrument_set.chamber is mock_chamber_instance
+            assert instrument_set.psu is mock_psu_instance
+            assert instrument_set.dmm is mock_dmm_instance
+
+    def test_factory_uses_custom_ports(self):
+        """Verify factory uses custom port configuration."""
+        from unittest.mock import patch
+
+        config = InstrumentConfig(
+            backend="simulator",
+            simulator_host="testserver",
+            chamber_port=7001,
+            psu_port=7002,
+            dmm_port=7003,
+        )
+
+        with patch(
+            "py_dvt_ate.instruments.transport.tcp.TCPTransport"
+        ) as mock_tcp_transport:
+            InstrumentFactory.create(config)
+
+            # Verify custom host and ports were used
+            mock_tcp_transport.assert_any_call("testserver", 7001)
+            mock_tcp_transport.assert_any_call("testserver", 7002)
+            mock_tcp_transport.assert_any_call("testserver", 7003)
+
+    def test_factory_returns_correct_types(self):
+        """Verify factory returns instruments implementing correct interfaces."""
+        from unittest.mock import Mock, patch
+
+        config = InstrumentConfig(backend="simulator")
+
+        with (
+            patch("py_dvt_ate.instruments.transport.tcp.TCPTransport"),
+            patch(
+                "py_dvt_ate.instruments.drivers.chamber.ThermalChamberDriver"
+            ) as mock_chamber,
+            patch(
+                "py_dvt_ate.instruments.drivers.power_supply.PowerSupplyDriver"
+            ) as mock_psu,
+            patch(
+                "py_dvt_ate.instruments.drivers.multimeter.MultimeterDriver"
+            ) as mock_dmm,
+        ):
+            # Make the mocks subclasses of the interfaces
+            mock_chamber.return_value = Mock(spec=IThermalChamber)
+            mock_psu.return_value = Mock(spec=IPowerSupply)
+            mock_dmm.return_value = Mock(spec=IMultimeter)
+
+            instrument_set = InstrumentFactory.create(config)
+
+            # Verify returned instruments satisfy the interface specs
+            # (Mock with spec=Interface makes isinstance checks work)
+            assert isinstance(instrument_set, InstrumentSet)

tests/unit/test_multimeter.py

@@ -0,0 +1,306 @@
+"""Unit tests for multimeter simulator."""
+
+import pytest
+
+from py_dvt_ate.simulation.physics.engine import PhysicsEngine
+from py_dvt_ate.simulation.virtual.multimeter import MultimeterSim
+
+
+class TestMultimeterSimBasic:
+    """Tests for MultimeterSim without physics engine."""
+
+    @pytest.fixture
+    def dmm(self) -> MultimeterSim:
+        """Create multimeter instance without physics engine."""
+        return MultimeterSim()
+
+    def test_creation(self, dmm: MultimeterSim) -> None:
+        """Test multimeter can be created."""
+        assert dmm is not None
+        assert dmm.model == "DMM-SIM-001"
+        assert dmm.manufacturer == "PyDVTATE"
+
+    def test_idn_query(self, dmm: MultimeterSim) -> None:
+        """Test *IDN? returns identification string."""
+        response = dmm.process("*IDN?")
+
+        assert "PyDVTATE" in response
+        assert "DMM-SIM-001" in response
+
+    def test_rst_command(self, dmm: MultimeterSim) -> None:
+        """Test *RST resets to defaults."""
+        # Set non-default config
+        dmm.process("CONF:CURR:DC")
+        assert dmm.process("CONF?") == '"CURR:DC"'
+
+        # Reset
+        response = dmm.process("*RST")
+        assert response == ""
+
+        # Check defaults restored
+        assert dmm.process("CONF?") == '"VOLT:DC"'
+
+    def test_opc_query(self, dmm: MultimeterSim) -> None:
+        """Test *OPC? returns 1."""
+        response = dmm.process("*OPC?")
+        assert response == "1"
+
+    def test_unknown_command(self, dmm: MultimeterSim) -> None:
+        """Test unknown command returns error."""
+        response = dmm.process("INVALID:CMD")
+
+        assert response.startswith("ERROR:")
+        assert "Unknown command" in response
+
+
+class TestMultimeterMeasVoltDC:
+    """Tests for MEAS:VOLT:DC command."""
+
+    @pytest.fixture
+    def dmm(self) -> MultimeterSim:
+        """Create multimeter instance without physics engine."""
+        return MultimeterSim()
+
+    def test_meas_volt_dc_query_no_engine(self, dmm: MultimeterSim) -> None:
+        """Test MEAS:VOLT:DC? returns 0 without physics engine."""
+        response = dmm.process("MEAS:VOLT:DC?")
+
+        assert response == "0.000000"
+
+    def test_meas_volt_dc_sets_config(self, dmm: MultimeterSim) -> None:
+        """Test MEAS:VOLT:DC? sets configuration to VOLT:DC."""
+        dmm.process("CONF:CURR:DC")
+        dmm.process("MEAS:VOLT:DC?")
+
+        assert dmm.process("CONF?") == '"VOLT:DC"'
+
+    def test_meas_volt_dc_as_command_fails(self, dmm: MultimeterSim) -> None:
+        """Test MEAS:VOLT:DC (without ?) returns error."""
+        response = dmm.process("MEAS:VOLT:DC 1.0")
+
+        assert response.startswith("ERROR:")
+        assert "query only" in response
+
+
+class TestMultimeterMeasCurrDC:
+    """Tests for MEAS:CURR:DC command."""
+
+    @pytest.fixture
+    def dmm(self) -> MultimeterSim:
+        """Create multimeter instance without physics engine."""
+        return MultimeterSim()
+
+    def test_meas_curr_dc_query_no_engine(self, dmm: MultimeterSim) -> None:
+        """Test MEAS:CURR:DC? returns 0 without physics engine."""
+        response = dmm.process("MEAS:CURR:DC?")
+
+        assert response == "0.000000"
+
+    def test_meas_curr_dc_sets_config(self, dmm: MultimeterSim) -> None:
+        """Test MEAS:CURR:DC? sets configuration to CURR:DC."""
+        dmm.process("MEAS:CURR:DC?")
+
+        assert dmm.process("CONF?") == '"CURR:DC"'
+
+    def test_meas_curr_dc_as_command_fails(self, dmm: MultimeterSim) -> None:
+        """Test MEAS:CURR:DC (without ?) returns error."""
+        response = dmm.process("MEAS:CURR:DC 0.1")
+
+        assert response.startswith("ERROR:")
+        assert "query only" in response
+
+
+class TestMultimeterConf:
+    """Tests for CONF commands."""
+
+    @pytest.fixture
+    def dmm(self) -> MultimeterSim:
+        """Create multimeter instance without physics engine."""
+        return MultimeterSim()
+
+    def test_conf_query_default(self, dmm: MultimeterSim) -> None:
+        """Test CONF? returns default configuration."""
+        response = dmm.process("CONF?")
+
+        assert response == '"VOLT:DC"'
+
+    def test_conf_volt_dc(self, dmm: MultimeterSim) -> None:
+        """Test CONF:VOLT:DC sets voltage measurement mode."""
+        dmm.process("CONF:CURR:DC")
+        response = dmm.process("CONF:VOLT:DC")
+
+        assert response == ""
+        assert dmm.process("CONF?") == '"VOLT:DC"'
+
+    def test_conf_volt_dc_as_query_fails(self, dmm: MultimeterSim) -> None:
+        """Test CONF:VOLT:DC? returns error."""
+        response = dmm.process("CONF:VOLT:DC?")
+
+        assert response.startswith("ERROR:")
+        assert "command only" in response
+
+    def test_conf_curr_dc(self, dmm: MultimeterSim) -> None:
+        """Test CONF:CURR:DC sets current measurement mode."""
+        response = dmm.process("CONF:CURR:DC")
+
+        assert response == ""
+        assert dmm.process("CONF?") == '"CURR:DC"'
+
+    def test_conf_curr_dc_as_query_fails(self, dmm: MultimeterSim) -> None:
+        """Test CONF:CURR:DC? returns error."""
+        response = dmm.process("CONF:CURR:DC?")
+
+        assert response.startswith("ERROR:")
+        assert "command only" in response
+
+    def test_conf_as_command_fails(self, dmm: MultimeterSim) -> None:
+        """Test CONF without subcommand returns error."""
+        response = dmm.process("CONF")
+
+        assert response.startswith("ERROR:")
+
+
+class TestMultimeterRead:
+    """Tests for READ command."""
+
+    @pytest.fixture
+    def dmm(self) -> MultimeterSim:
+        """Create multimeter instance without physics engine."""
+        return MultimeterSim()
+
+    def test_read_query_volt_mode(self, dmm: MultimeterSim) -> None:
+        """Test READ? returns voltage when configured for voltage."""
+        dmm.process("CONF:VOLT:DC")
+        response = dmm.process("READ?")
+
+        assert response == "0.000000"
+
+    def test_read_query_curr_mode(self, dmm: MultimeterSim) -> None:
+        """Test READ? returns current when configured for current."""
+        dmm.process("CONF:CURR:DC")
+        response = dmm.process("READ?")
+
+        assert response == "0.000000"
+
+    def test_read_as_command_fails(self, dmm: MultimeterSim) -> None:
+        """Test READ (without ?) returns error."""
+        response = dmm.process("READ")
+
+        assert response.startswith("ERROR:")
+        assert "query only" in response
+
+
+class TestMultimeterWithPhysicsEngine:
+    """Tests for MultimeterSim with physics engine integration."""
+
+    @pytest.fixture
+    def engine(self) -> PhysicsEngine:
+        """Create physics engine instance."""
+        return PhysicsEngine(update_rate_hz=100.0)
+
+    @pytest.fixture
+    def dmm(self, engine: PhysicsEngine) -> MultimeterSim:
+        """Create multimeter instance with physics engine."""
+        return MultimeterSim(physics_engine=engine)
+
+    def test_meas_volt_dc_returns_engine_voltage(
+        self, dmm: MultimeterSim, engine: PhysicsEngine
+    ) -> None:
+        """Test MEAS:VOLT:DC? returns physics engine output voltage."""
+        engine.set_input_voltage(5.0)
+        engine.set_output_enabled(True)
+        engine.step()
+
+        response = dmm.process("MEAS:VOLT:DC?")
+
+        # LDO model outputs ~3.3V nominal
+        voltage = float(response)
+        assert voltage > 3.0
+        assert voltage < 4.0
+
+    def test_meas_volt_dc_returns_zero_when_disabled(
+        self, dmm: MultimeterSim, engine: PhysicsEngine
+    ) -> None:
+        """Test MEAS:VOLT:DC? returns 0 when DUT output disabled."""
+        engine.set_input_voltage(5.0)
+        engine.set_output_enabled(False)
+        engine.step()
+
+        response = dmm.process("MEAS:VOLT:DC?")
+
+        assert response == "0.000000"
+
+    def test_meas_curr_dc_returns_engine_current(
+        self, dmm: MultimeterSim, engine: PhysicsEngine
+    ) -> None:
+        """Test MEAS:CURR:DC? returns physics engine load current."""
+        engine.set_input_voltage(5.0)
+        engine.set_load_current(0.1)
+        engine.set_output_enabled(True)
+        engine.step()
+
+        response = dmm.process("MEAS:CURR:DC?")
+
+        assert float(response) == pytest.approx(0.1, abs=0.001)
+
+    def test_meas_curr_dc_returns_zero_when_disabled(
+        self, dmm: MultimeterSim, engine: PhysicsEngine
+    ) -> None:
+        """Test MEAS:CURR:DC? returns 0 when DUT output disabled."""
+        engine.set_input_voltage(5.0)
+        engine.set_load_current(0.1)
+        engine.set_output_enabled(False)
+        engine.step()
+
+        response = dmm.process("MEAS:CURR:DC?")
+
+        assert response == "0.000000"
+
+    def test_read_uses_configured_function(
+        self, dmm: MultimeterSim, engine: PhysicsEngine
+    ) -> None:
+        """Test READ? respects configured measurement function."""
+        engine.set_input_voltage(5.0)
+        engine.set_load_current(0.1)
+        engine.set_output_enabled(True)
+        engine.step()
+
+        # Configure for current
+        dmm.process("CONF:CURR:DC")
+        response = dmm.process("READ?")
+
+        # Should return current, not voltage
+        assert float(response) == pytest.approx(0.1, abs=0.001)
+
+    def test_reset_restores_voltage_mode(
+        self, dmm: MultimeterSim, engine: PhysicsEngine
+    ) -> None:
+        """Test *RST restores default voltage measurement mode."""
+        dmm.process("CONF:CURR:DC")
+        dmm.process("*RST")
+
+        assert dmm.process("CONF?") == '"VOLT:DC"'
+
+    def test_voltage_changes_with_temperature(
+        self, dmm: MultimeterSim, engine: PhysicsEngine
+    ) -> None:
+        """Test measured voltage changes with DUT temperature."""
+        engine.set_input_voltage(5.0)
+        engine.set_output_enabled(True)
+        engine.step()
+
+        # Measure at initial temperature
+        response1 = dmm.process("MEAS:VOLT:DC?")
+        v1 = float(response1)
+
+        # Change chamber temperature and let settle
+        engine.set_chamber_setpoint(85.0)
+        for _ in range(5000):  # Let temperature settle somewhat
+            engine.step()
+
+        # Measure at elevated temperature
+        response2 = dmm.process("MEAS:VOLT:DC?")
+        v2 = float(response2)
+
+        # Output voltage should have changed (LDO has tempco)
+        assert v1 != v2

tests/unit/test_physics_models.py

@@ -63,7 +63,7 @@ class TestThermalState:
 
         # Should not raise
         hash(state)
-        {state}  # Can be added to a set
+        _ = {state}  # Can be added to a set
 
 
 class TestElectricalState:

tests/unit/test_power_supply.py

@@ -0,0 +1,352 @@
+"""Unit tests for power supply simulator."""
+
+import pytest
+
+from py_dvt_ate.simulation.physics.engine import PhysicsEngine
+from py_dvt_ate.simulation.virtual.power_supply import PowerSupplySim
+
+
+class TestPowerSupplySimBasic:
+    """Tests for PowerSupplySim without physics engine."""
+
+    @pytest.fixture
+    def psu(self) -> PowerSupplySim:
+        """Create power supply instance without physics engine."""
+        return PowerSupplySim()
+
+    def test_creation(self, psu: PowerSupplySim) -> None:
+        """Test power supply can be created."""
+        assert psu is not None
+        assert psu.model == "PS-SIM-001"
+        assert psu.manufacturer == "PyDVTATE"
+
+    def test_idn_query(self, psu: PowerSupplySim) -> None:
+        """Test *IDN? returns identification string."""
+        response = psu.process("*IDN?")
+
+        assert "PyDVTATE" in response
+        assert "PS-SIM-001" in response
+
+    def test_rst_command(self, psu: PowerSupplySim) -> None:
+        """Test *RST resets to defaults."""
+        # Set non-default values
+        psu.process("VOLT 12.0")
+        psu.process("CURR 2.0")
+        psu.process("OUTP ON")
+
+        # Reset
+        response = psu.process("*RST")
+        assert response == ""
+
+        # Check defaults restored
+        assert psu.process("VOLT?") == "0.000"
+        assert psu.process("CURR?") == "1.000"
+        assert psu.process("OUTP?") == "0"
+
+    def test_opc_query(self, psu: PowerSupplySim) -> None:
+        """Test *OPC? returns 1."""
+        response = psu.process("*OPC?")
+        assert response == "1"
+
+    def test_unknown_command(self, psu: PowerSupplySim) -> None:
+        """Test unknown command returns error."""
+        response = psu.process("INVALID:CMD")
+
+        assert response.startswith("ERROR:")
+        assert "Unknown command" in response
+
+
+class TestPowerSupplyVoltage:
+    """Tests for VOLT command."""
+
+    @pytest.fixture
+    def psu(self) -> PowerSupplySim:
+        """Create power supply instance without physics engine."""
+        return PowerSupplySim()
+
+    def test_volt_query_default(self, psu: PowerSupplySim) -> None:
+        """Test VOLT? returns default value."""
+        response = psu.process("VOLT?")
+
+        assert response == "0.000"
+
+    def test_volt_set(self, psu: PowerSupplySim) -> None:
+        """Test VOLT sets value."""
+        response = psu.process("VOLT 12.5")
+
+        assert response == ""
+        assert psu.process("VOLT?") == "12.500"
+
+    def test_volt_set_decimal(self, psu: PowerSupplySim) -> None:
+        """Test VOLT accepts decimal values."""
+        psu.process("VOLT 3.3")
+
+        assert psu.process("VOLT?") == "3.300"
+
+    def test_volt_set_negative_fails(self, psu: PowerSupplySim) -> None:
+        """Test VOLT rejects negative values."""
+        response = psu.process("VOLT -5.0")
+
+        assert response.startswith("ERROR:")
+        assert "negative" in response
+
+    def test_volt_set_invalid_value(self, psu: PowerSupplySim) -> None:
+        """Test VOLT with invalid value returns error."""
+        response = psu.process("VOLT abc")
+
+        assert response.startswith("ERROR:")
+        assert "Invalid voltage" in response
+
+    def test_volt_set_no_argument(self, psu: PowerSupplySim) -> None:
+        """Test VOLT without argument returns error."""
+        response = psu.process("VOLT")
+
+        assert response.startswith("ERROR:")
+        assert "requires a value" in response
+
+
+class TestPowerSupplyCurrent:
+    """Tests for CURR command."""
+
+    @pytest.fixture
+    def psu(self) -> PowerSupplySim:
+        """Create power supply instance without physics engine."""
+        return PowerSupplySim()
+
+    def test_curr_query_default(self, psu: PowerSupplySim) -> None:
+        """Test CURR? returns default value."""
+        response = psu.process("CURR?")
+
+        assert response == "1.000"
+
+    def test_curr_set(self, psu: PowerSupplySim) -> None:
+        """Test CURR sets value."""
+        response = psu.process("CURR 0.5")
+
+        assert response == ""
+        assert psu.process("CURR?") == "0.500"
+
+    def test_curr_set_negative_fails(self, psu: PowerSupplySim) -> None:
+        """Test CURR rejects negative values."""
+        response = psu.process("CURR -1.0")
+
+        assert response.startswith("ERROR:")
+        assert "negative" in response
+
+    def test_curr_set_invalid_value(self, psu: PowerSupplySim) -> None:
+        """Test CURR with invalid value returns error."""
+        response = psu.process("CURR xyz")
+
+        assert response.startswith("ERROR:")
+        assert "Invalid current" in response
+
+    def test_curr_set_no_argument(self, psu: PowerSupplySim) -> None:
+        """Test CURR without argument returns error."""
+        response = psu.process("CURR")
+
+        assert response.startswith("ERROR:")
+        assert "requires a value" in response
+
+
+class TestPowerSupplyOutput:
+    """Tests for OUTP command."""
+
+    @pytest.fixture
+    def psu(self) -> PowerSupplySim:
+        """Create power supply instance without physics engine."""
+        return PowerSupplySim()
+
+    def test_outp_query_default(self, psu: PowerSupplySim) -> None:
+        """Test OUTP? returns default value (off)."""
+        response = psu.process("OUTP?")
+
+        assert response == "0"
+
+    def test_outp_set_on(self, psu: PowerSupplySim) -> None:
+        """Test OUTP ON enables output."""
+        response = psu.process("OUTP ON")
+
+        assert response == ""
+        assert psu.process("OUTP?") == "1"
+
+    def test_outp_set_1(self, psu: PowerSupplySim) -> None:
+        """Test OUTP 1 enables output."""
+        psu.process("OUTP 1")
+
+        assert psu.process("OUTP?") == "1"
+
+    def test_outp_set_off(self, psu: PowerSupplySim) -> None:
+        """Test OUTP OFF disables output."""
+        psu.process("OUTP ON")
+        psu.process("OUTP OFF")
+
+        assert psu.process("OUTP?") == "0"
+
+    def test_outp_set_0(self, psu: PowerSupplySim) -> None:
+        """Test OUTP 0 disables output."""
+        psu.process("OUTP ON")
+        psu.process("OUTP 0")
+
+        assert psu.process("OUTP?") == "0"
+
+    def test_outp_set_invalid(self, psu: PowerSupplySim) -> None:
+        """Test OUTP with invalid value returns error."""
+        response = psu.process("OUTP MAYBE")
+
+        assert response.startswith("ERROR:")
+        assert "Invalid output state" in response
+
+    def test_outp_set_no_argument(self, psu: PowerSupplySim) -> None:
+        """Test OUTP without argument returns error."""
+        response = psu.process("OUTP")
+
+        assert response.startswith("ERROR:")
+        assert "requires a value" in response
+
+
+class TestPowerSupplyMeasurement:
+    """Tests for MEAS commands."""
+
+    @pytest.fixture
+    def psu(self) -> PowerSupplySim:
+        """Create power supply instance without physics engine."""
+        return PowerSupplySim()
+
+    def test_meas_volt_when_off(self, psu: PowerSupplySim) -> None:
+        """Test MEAS:VOLT? returns 0 when output is off."""
+        psu.process("VOLT 12.0")
+        response = psu.process("MEAS:VOLT?")
+
+        assert response == "0.000"
+
+    def test_meas_volt_when_on_no_engine(self, psu: PowerSupplySim) -> None:
+        """Test MEAS:VOLT? returns setpoint when on without engine."""
+        psu.process("VOLT 12.0")
+        psu.process("OUTP ON")
+        response = psu.process("MEAS:VOLT?")
+
+        assert response == "12.000"
+
+    def test_meas_volt_as_command_fails(self, psu: PowerSupplySim) -> None:
+        """Test MEAS:VOLT (without ?) returns error."""
+        response = psu.process("MEAS:VOLT 5.0")
+
+        assert response.startswith("ERROR:")
+        assert "query only" in response
+
+    def test_meas_curr_when_off(self, psu: PowerSupplySim) -> None:
+        """Test MEAS:CURR? returns 0 when output is off."""
+        response = psu.process("MEAS:CURR?")
+
+        assert response == "0.000"
+
+    def test_meas_curr_when_on_no_engine(self, psu: PowerSupplySim) -> None:
+        """Test MEAS:CURR? returns 0 when on without engine."""
+        psu.process("OUTP ON")
+        response = psu.process("MEAS:CURR?")
+
+        assert response == "0.000"
+
+    def test_meas_curr_as_command_fails(self, psu: PowerSupplySim) -> None:
+        """Test MEAS:CURR (without ?) returns error."""
+        response = psu.process("MEAS:CURR 0.1")
+
+        assert response.startswith("ERROR:")
+        assert "query only" in response
+
+
+class TestPowerSupplyWithPhysicsEngine:
+    """Tests for PowerSupplySim with physics engine integration."""
+
+    @pytest.fixture
+    def engine(self) -> PhysicsEngine:
+        """Create physics engine instance."""
+        return PhysicsEngine(update_rate_hz=100.0)
+
+    @pytest.fixture
+    def psu(self, engine: PhysicsEngine) -> PowerSupplySim:
+        """Create power supply instance with physics engine."""
+        return PowerSupplySim(physics_engine=engine)
+
+    def test_outp_on_enables_engine_output(
+        self, psu: PowerSupplySim, engine: PhysicsEngine
+    ) -> None:
+        """Test OUTP ON enables physics engine output."""
+        psu.process("VOLT 5.0")
+        psu.process("OUTP ON")
+
+        assert engine.is_output_enabled is True
+
+    def test_outp_off_disables_engine_output(
+        self, psu: PowerSupplySim, engine: PhysicsEngine
+    ) -> None:
+        """Test OUTP OFF disables physics engine output."""
+        psu.process("OUTP ON")
+        psu.process("OUTP OFF")
+
+        assert engine.is_output_enabled is False
+
+    def test_volt_updates_engine_when_on(
+        self, psu: PowerSupplySim, engine: PhysicsEngine
+    ) -> None:
+        """Test VOLT updates engine input voltage when output is on."""
+        psu.process("OUTP ON")
+        psu.process("VOLT 5.0")
+
+        electrical = engine.get_electrical_state()
+        assert electrical.input_voltage == pytest.approx(5.0)
+
+    def test_volt_does_not_update_engine_when_off(
+        self, psu: PowerSupplySim, engine: PhysicsEngine
+    ) -> None:
+        """Test VOLT does not update engine when output is off."""
+        psu.process("VOLT 5.0")
+
+        electrical = engine.get_electrical_state()
+        assert electrical.input_voltage == pytest.approx(0.0)
+
+    def test_meas_volt_returns_engine_voltage(
+        self, psu: PowerSupplySim, engine: PhysicsEngine
+    ) -> None:
+        """Test MEAS:VOLT? returns physics engine voltage."""
+        psu.process("VOLT 5.0")
+        psu.process("OUTP ON")
+
+        response = psu.process("MEAS:VOLT?")
+        assert response == "5.000"
+
+    def test_meas_curr_returns_engine_current(
+        self, psu: PowerSupplySim, engine: PhysicsEngine
+    ) -> None:
+        """Test MEAS:CURR? returns total current from engine."""
+        psu.process("VOLT 5.0")
+        psu.process("OUTP ON")
+        engine.set_load_current(0.1)
+
+        # Step engine to allow calculations
+        engine.step()
+
+        response = psu.process("MEAS:CURR?")
+        # Should include load current + quiescent current
+        assert float(response) > 0.0
+
+    def test_reset_disables_engine_output(
+        self, psu: PowerSupplySim, engine: PhysicsEngine
+    ) -> None:
+        """Test *RST disables physics engine output."""
+        psu.process("VOLT 5.0")
+        psu.process("OUTP ON")
+        psu.process("*RST")
+
+        assert engine.is_output_enabled is False
+
+    def test_reset_sets_engine_voltage_zero(
+        self, psu: PowerSupplySim, engine: PhysicsEngine
+    ) -> None:
+        """Test *RST sets physics engine voltage to zero."""
+        psu.process("VOLT 5.0")
+        psu.process("OUTP ON")
+        psu.process("*RST")
+
+        electrical = engine.get_electrical_state()
+        assert electrical.input_voltage == pytest.approx(0.0)

tests/unit/test_repository.py

@@ -0,0 +1,295 @@
+"""Unit tests for data repository."""
+
+import tempfile
+from pathlib import Path
+from uuid import uuid4
+
+import pandas as pd
+import pytest
+
+from py_dvt_ate.data.models import Measurement, TestStatus
+from py_dvt_ate.data.repository import SQLiteRepository
+
+
+@pytest.fixture
+def temp_db():
+    """Create a temporary database for testing."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        db_path = Path(tmpdir) / "test.db"
+        yield db_path
+
+
+@pytest.fixture
+def repository(temp_db):
+    """Create a repository instance for testing."""
+    return SQLiteRepository(temp_db)
+
+
+def test_create_run(repository):
+    """Test creating a new test run."""
+    config = {"temperature": 25.0, "voltage": 3.3}
+    run_id = repository.create_run(
+        test_name="TempCo Test",
+        config=config,
+        operator="Test Engineer",
+        description="Test description",
+    )
+
+    assert run_id is not None
+
+    # Verify run was created
+    run = repository.get_run(run_id)
+    assert run.test_name == "TempCo Test"
+    assert run.operator == "Test Engineer"
+    assert run.description == "Test description"
+    assert run.status == TestStatus.PENDING
+
+
+def test_update_run_status(repository):
+    """Test updating test run status."""
+    run_id = repository.create_run("Test", config={})
+
+    repository.update_run_status(run_id, TestStatus.RUNNING)
+    run = repository.get_run(run_id)
+    assert run.status == TestStatus.RUNNING
+
+    repository.update_run_status(run_id, TestStatus.PASSED)
+    run = repository.get_run(run_id)
+    assert run.status == TestStatus.PASSED
+
+
+def test_complete_run(repository):
+    """Test completing a test run."""
+    run_id = repository.create_run("Test", config={})
+
+    repository.complete_run(run_id, TestStatus.PASSED)
+    run = repository.get_run(run_id)
+
+    assert run.status == TestStatus.PASSED
+    assert run.completed_at is not None
+
+
+def test_save_result(repository):
+    """Test saving a test result."""
+    run_id = repository.create_run("Test", config={})
+
+    repository.save_result(
+        run_id=run_id,
+        parameter="output_voltage",
+        value=3.305,
+        unit="V",
+        lower_limit=3.267,
+        upper_limit=3.333,
+    )
+
+    results = repository.get_results(run_id)
+    assert len(results) == 1
+
+    result = results[0]
+    assert result.parameter == "output_voltage"
+    assert result.value == 3.305
+    assert result.unit == "V"
+    assert result.lower_limit == 3.267
+    assert result.upper_limit == 3.333
+    assert result.passed is True
+
+
+def test_save_result_fail(repository):
+    """Test saving a failing test result."""
+    run_id = repository.create_run("Test", config={})
+
+    repository.save_result(
+        run_id=run_id,
+        parameter="output_voltage",
+        value=3.350,  # Outside upper limit
+        unit="V",
+        lower_limit=3.267,
+        upper_limit=3.333,
+    )
+
+    results = repository.get_results(run_id)
+    result = results[0]
+    assert result.passed is False
+
+
+def test_save_result_no_limits(repository):
+    """Test saving a result without limits."""
+    run_id = repository.create_run("Test", config={})
+
+    repository.save_result(
+        run_id=run_id,
+        parameter="temperature",
+        value=25.5,
+        unit="°C",
+    )
+
+    results = repository.get_results(run_id)
+    result = results[0]
+    assert result.passed is None  # No limits defined
+
+
+def test_save_measurements(repository):
+    """Test saving time-series measurements to Parquet."""
+    run_id = repository.create_run("Test", config={})
+
+    measurements = [
+        Measurement(
+            timestamp=1234567890.0,
+            parameter="voltage",
+            value=3.3,
+            unit="V",
+            temperature=25.0,
+            input_voltage=5.0,
+            load_current=0.1,
+        ),
+        Measurement(
+            timestamp=1234567891.0,
+            parameter="voltage",
+            value=3.31,
+            unit="V",
+            temperature=25.1,
+            input_voltage=5.0,
+            load_current=0.1,
+        ),
+    ]
+
+    repository.save_measurements(run_id, measurements)
+
+    # Verify measurements were saved
+    df = repository.get_measurements_dataframe(run_id)
+    assert df is not None
+    assert len(df) == 2
+    assert list(df["parameter"]) == ["voltage", "voltage"]
+    assert list(df["value"]) == [3.3, 3.31]
+
+
+def test_save_measurements_append(repository):
+    """Test appending measurements to existing Parquet file."""
+    run_id = repository.create_run("Test", config={})
+
+    # Save first batch
+    measurements1 = [
+        Measurement(
+            timestamp=1234567890.0,
+            parameter="voltage",
+            value=3.3,
+            unit="V",
+        )
+    ]
+    repository.save_measurements(run_id, measurements1)
+
+    # Save second batch
+    measurements2 = [
+        Measurement(
+            timestamp=1234567891.0,
+            parameter="voltage",
+            value=3.31,
+            unit="V",
+        )
+    ]
+    repository.save_measurements(run_id, measurements2)
+
+    # Verify both batches are present
+    df = repository.get_measurements_dataframe(run_id)
+    assert df is not None
+    assert len(df) == 2
+
+
+def test_get_measurements_nonexistent(repository):
+    """Test getting measurements for non-existent run."""
+    fake_id = uuid4()
+    df = repository.get_measurements_dataframe(fake_id)
+    assert df is None
+
+
+def test_save_empty_measurements(repository):
+    """Test saving empty measurement list."""
+    run_id = repository.create_run("Test", config={})
+    repository.save_measurements(run_id, [])
+
+    df = repository.get_measurements_dataframe(run_id)
+    assert df is None
+
+
+def test_get_nonexistent_run(repository):
+    """Test getting a non-existent run raises error."""
+    fake_id = uuid4()
+    with pytest.raises(ValueError, match="not found"):
+        repository.get_run(fake_id)
+
+
+def test_multiple_results(repository):
+    """Test saving and retrieving multiple results."""
+    run_id = repository.create_run("Test", config={})
+
+    repository.save_result(run_id, "voltage", 3.3, "V")
+    repository.save_result(run_id, "current", 50.0, "uA")
+    repository.save_result(run_id, "temperature", 25.0, "°C")
+
+    results = repository.get_results(run_id)
+    assert len(results) == 3
+
+    parameters = {r.parameter for r in results}
+    assert parameters == {"voltage", "current", "temperature"}
+
+
+def test_custom_measurements_dir(temp_db):
+    """Test using a custom measurements directory."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        measurements_dir = Path(tmpdir) / "custom_measurements"
+        repo = SQLiteRepository(temp_db, measurements_dir=measurements_dir)
+
+        run_id = repo.create_run("Test", config={})
+        measurements = [
+            Measurement(
+                timestamp=1234567890.0,
+                parameter="voltage",
+                value=3.3,
+                unit="V",
+            )
+        ]
+        repo.save_measurements(run_id, measurements)
+
+        # Verify file is in custom directory
+        expected_path = measurements_dir / f"run_{run_id}" / "measurements.parquet"
+        assert expected_path.exists()
+
+
+def test_parquet_schema(repository):
+    """Test that Parquet file has correct schema."""
+    run_id = repository.create_run("Test", config={})
+
+    measurements = [
+        Measurement(
+            timestamp=1234567890.123,
+            parameter="voltage",
+            value=3.3,
+            unit="V",
+            temperature=25.5,
+            input_voltage=5.0,
+            load_current=0.1,
+        )
+    ]
+    repository.save_measurements(run_id, measurements)
+
+    df = repository.get_measurements_dataframe(run_id)
+    assert df is not None
+
+    # Check columns
+    expected_columns = {
+        "timestamp",
+        "parameter",
+        "value",
+        "unit",
+        "temperature",
+        "input_voltage",
+        "load_current",
+    }
+    assert set(df.columns) == expected_columns
+
+    # Check data types (approximately)
+    assert pd.api.types.is_float_dtype(df["timestamp"])
+    assert pd.api.types.is_string_dtype(df["parameter"]) or pd.api.types.is_object_dtype(
+        df["parameter"]
+    )
+    assert pd.api.types.is_float_dtype(df["value"])

tests/unit/test_scpi_parser.py

@@ -0,0 +1,203 @@
+"""Unit tests for SCPI command parsing."""
+
+import pytest
+
+from py_dvt_ate.instruments.scpi import SCPICommand, SCPIParser
+
+
+class TestSCPICommand:
+    """Tests for the SCPICommand dataclass."""
+
+    def test_creation(self) -> None:
+        """Test SCPICommand can be created with valid values."""
+        cmd = SCPICommand(
+            header="VOLT",
+            arguments=["3.3"],
+            is_query=False,
+        )
+
+        assert cmd.header == "VOLT"
+        assert cmd.arguments == ["3.3"]
+        assert cmd.is_query is False
+
+    def test_keyword_for_command(self) -> None:
+        """Test keyword property for regular command."""
+        cmd = SCPICommand(header="VOLT", arguments=["3.3"], is_query=False)
+
+        assert cmd.keyword == "VOLT"
+
+    def test_keyword_for_query(self) -> None:
+        """Test keyword property strips '?' from query."""
+        cmd = SCPICommand(header="VOLT?", arguments=[], is_query=True)
+
+        assert cmd.keyword == "VOLT"
+
+    def test_keyword_for_nested_command(self) -> None:
+        """Test keyword property for nested SCPI command."""
+        cmd = SCPICommand(header="TEMP:SETPOINT?", arguments=[], is_query=True)
+
+        assert cmd.keyword == "TEMP:SETPOINT"
+
+
+class TestSCPIParser:
+    """Tests for the SCPIParser class."""
+
+    @pytest.fixture
+    def parser(self) -> SCPIParser:
+        """Create parser instance for tests."""
+        return SCPIParser()
+
+    def test_parse_simple_query(self, parser: SCPIParser) -> None:
+        """Test parsing simple query command."""
+        cmd = parser.parse("*IDN?")
+
+        assert cmd.header == "*IDN?"
+        assert cmd.arguments == []
+        assert cmd.is_query is True
+        assert cmd.keyword == "*IDN"
+
+    def test_parse_simple_command(self, parser: SCPIParser) -> None:
+        """Test parsing simple command without arguments."""
+        cmd = parser.parse("*RST")
+
+        assert cmd.header == "*RST"
+        assert cmd.arguments == []
+        assert cmd.is_query is False
+        assert cmd.keyword == "*RST"
+
+    def test_parse_command_with_single_argument(self, parser: SCPIParser) -> None:
+        """Test parsing command with single numeric argument."""
+        cmd = parser.parse("VOLT 3.3")
+
+        assert cmd.header == "VOLT"
+        assert cmd.arguments == ["3.3"]
+        assert cmd.is_query is False
+
+    def test_parse_command_with_multiple_arguments(self, parser: SCPIParser) -> None:
+        """Test parsing command with comma-separated arguments."""
+        cmd = parser.parse("CONF:VOLT:DC 10,0.001")
+
+        assert cmd.header == "CONF:VOLT:DC"
+        assert cmd.arguments == ["10", "0.001"]
+        assert cmd.is_query is False
+
+    def test_parse_nested_scpi_command(self, parser: SCPIParser) -> None:
+        """Test parsing nested SCPI command hierarchy."""
+        cmd = parser.parse("TEMP:SETPOINT 85.0")
+
+        assert cmd.header == "TEMP:SETPOINT"
+        assert cmd.arguments == ["85.0"]
+        assert cmd.is_query is False
+        assert cmd.keyword == "TEMP:SETPOINT"
+
+    def test_parse_nested_scpi_query(self, parser: SCPIParser) -> None:
+        """Test parsing nested SCPI query."""
+        cmd = parser.parse("TEMP:SETPOINT?")
+
+        assert cmd.header == "TEMP:SETPOINT?"
+        assert cmd.arguments == []
+        assert cmd.is_query is True
+
+    def test_parse_ieee_common_commands(self, parser: SCPIParser) -> None:
+        """Test parsing IEEE 488.2 common commands."""
+        # Identity query
+        cmd = parser.parse("*IDN?")
+        assert cmd.is_query is True
+        assert cmd.keyword == "*IDN"
+
+        # Reset
+        cmd = parser.parse("*RST")
+        assert cmd.is_query is False
+        assert cmd.keyword == "*RST"
+
+        # Clear status
+        cmd = parser.parse("*CLS")
+        assert cmd.is_query is False
+        assert cmd.keyword == "*CLS"
+
+        # Operation complete query
+        cmd = parser.parse("*OPC?")
+        assert cmd.is_query is True
+        assert cmd.keyword == "*OPC"
+
+    def test_parse_strips_whitespace(self, parser: SCPIParser) -> None:
+        """Test parser strips leading and trailing whitespace."""
+        cmd = parser.parse("  VOLT 3.3  ")
+
+        assert cmd.header == "VOLT"
+        assert cmd.arguments == ["3.3"]
+
+    def test_parse_strips_argument_whitespace(self, parser: SCPIParser) -> None:
+        """Test parser strips whitespace from arguments."""
+        cmd = parser.parse("CONF:VOLT:DC  10 , 0.001 ")
+
+        assert cmd.arguments == ["10", "0.001"]
+
+    def test_parse_empty_string(self, parser: SCPIParser) -> None:
+        """Test parsing empty string returns empty command."""
+        cmd = parser.parse("")
+
+        assert cmd.header == ""
+        assert cmd.arguments == []
+        assert cmd.is_query is False
+
+    def test_parse_whitespace_only(self, parser: SCPIParser) -> None:
+        """Test parsing whitespace-only string returns empty command."""
+        cmd = parser.parse("   ")
+
+        assert cmd.header == ""
+        assert cmd.arguments == []
+        assert cmd.is_query is False
+
+    def test_parse_output_on_off(self, parser: SCPIParser) -> None:
+        """Test parsing output enable/disable commands."""
+        cmd_on = parser.parse("OUTP ON")
+        assert cmd_on.arguments == ["ON"]
+
+        cmd_off = parser.parse("OUTP OFF")
+        assert cmd_off.arguments == ["OFF"]
+
+        cmd_1 = parser.parse("OUTP 1")
+        assert cmd_1.arguments == ["1"]
+
+        cmd_0 = parser.parse("OUTP 0")
+        assert cmd_0.arguments == ["0"]
+
+    def test_parse_channel_select(self, parser: SCPIParser) -> None:
+        """Test parsing channel selection commands."""
+        cmd = parser.parse("INST:SEL CH1")
+
+        assert cmd.header == "INST:SEL"
+        assert cmd.arguments == ["CH1"]
+
+    def test_parse_measurement_query(self, parser: SCPIParser) -> None:
+        """Test parsing measurement query commands."""
+        cmd = parser.parse("MEAS:VOLT:DC?")
+
+        assert cmd.header == "MEAS:VOLT:DC?"
+        assert cmd.is_query is True
+        assert cmd.keyword == "MEAS:VOLT:DC"
+
+    def test_parse_measurement_with_range(self, parser: SCPIParser) -> None:
+        """Test parsing measurement query with range argument."""
+        cmd = parser.parse("MEAS:VOLT:DC? AUTO")
+
+        assert cmd.header == "MEAS:VOLT:DC?"
+        assert cmd.arguments == ["AUTO"]
+        assert cmd.is_query is True
+
+    def test_parse_system_error_query(self, parser: SCPIParser) -> None:
+        """Test parsing system error query."""
+        cmd = parser.parse("SYST:ERR?")
+
+        assert cmd.header == "SYST:ERR?"
+        assert cmd.is_query is True
+        assert cmd.keyword == "SYST:ERR"
+
+    def test_parse_nplc_setting(self, parser: SCPIParser) -> None:
+        """Test parsing NPLC (integration time) command."""
+        cmd = parser.parse("SENS:VOLT:DC:NPLC 10")
+
+        assert cmd.header == "SENS:VOLT:DC:NPLC"
+        assert cmd.arguments == ["10"]
+        assert cmd.is_query is False

tests/unit/test_thermal_chamber.py

@@ -0,0 +1,215 @@
+"""Unit tests for thermal chamber simulator."""
+
+import pytest
+
+from py_dvt_ate.simulation.physics.engine import PhysicsEngine
+from py_dvt_ate.simulation.virtual.chamber import ThermalChamberSim
+
+
+class TestThermalChamberSimBasic:
+    """Tests for ThermalChamberSim without physics engine."""
+
+    @pytest.fixture
+    def chamber(self) -> ThermalChamberSim:
+        """Create chamber instance without physics engine."""
+        return ThermalChamberSim()
+
+    def test_creation(self, chamber: ThermalChamberSim) -> None:
+        """Test chamber can be created."""
+        assert chamber is not None
+        assert chamber.model == "TC-SIM-001"
+        assert chamber.manufacturer == "PyDVTATE"
+
+    def test_idn_query(self, chamber: ThermalChamberSim) -> None:
+        """Test *IDN? returns identification string."""
+        response = chamber.process("*IDN?")
+
+        assert "PyDVTATE" in response
+        assert "TC-SIM-001" in response
+
+    def test_rst_command(self, chamber: ThermalChamberSim) -> None:
+        """Test *RST resets to defaults."""
+        # Set non-default value
+        chamber.process("TEMP:SETPOINT 85.0")
+        assert chamber.process("TEMP:SETPOINT?") == "85.00"
+
+        # Reset
+        response = chamber.process("*RST")
+        assert response == ""
+        assert chamber.process("TEMP:SETPOINT?") == "25.00"
+
+    def test_opc_query(self, chamber: ThermalChamberSim) -> None:
+        """Test *OPC? returns 1."""
+        response = chamber.process("*OPC?")
+        assert response == "1"
+
+    def test_unknown_command(self, chamber: ThermalChamberSim) -> None:
+        """Test unknown command returns error."""
+        response = chamber.process("INVALID:CMD")
+
+        assert response.startswith("ERROR:")
+        assert "Unknown command" in response
+
+
+class TestThermalChamberSetpoint:
+    """Tests for TEMP:SETPOINT command."""
+
+    @pytest.fixture
+    def chamber(self) -> ThermalChamberSim:
+        """Create chamber instance without physics engine."""
+        return ThermalChamberSim()
+
+    def test_setpoint_query_default(self, chamber: ThermalChamberSim) -> None:
+        """Test TEMP:SETPOINT? returns default value."""
+        response = chamber.process("TEMP:SETPOINT?")
+
+        assert response == "25.00"
+
+    def test_setpoint_set(self, chamber: ThermalChamberSim) -> None:
+        """Test TEMP:SETPOINT sets value."""
+        response = chamber.process("TEMP:SETPOINT 85.0")
+
+        assert response == ""
+        assert chamber.process("TEMP:SETPOINT?") == "85.00"
+
+    def test_setpoint_set_negative(self, chamber: ThermalChamberSim) -> None:
+        """Test TEMP:SETPOINT accepts negative values."""
+        chamber.process("TEMP:SETPOINT -40.0")
+
+        assert chamber.process("TEMP:SETPOINT?") == "-40.00"
+
+    def test_setpoint_set_invalid_value(self, chamber: ThermalChamberSim) -> None:
+        """Test TEMP:SETPOINT with invalid value returns error."""
+        response = chamber.process("TEMP:SETPOINT abc")
+
+        assert response.startswith("ERROR:")
+        assert "Invalid temperature" in response
+
+    def test_setpoint_set_no_argument(self, chamber: ThermalChamberSim) -> None:
+        """Test TEMP:SETPOINT without argument returns error."""
+        response = chamber.process("TEMP:SETPOINT")
+
+        assert response.startswith("ERROR:")
+        assert "requires a value" in response
+
+
+class TestThermalChamberActual:
+    """Tests for TEMP:ACTUAL? query."""
+
+    @pytest.fixture
+    def chamber(self) -> ThermalChamberSim:
+        """Create chamber instance without physics engine."""
+        return ThermalChamberSim()
+
+    def test_actual_query_without_engine(self, chamber: ThermalChamberSim) -> None:
+        """Test TEMP:ACTUAL? returns setpoint when no physics engine."""
+        chamber.process("TEMP:SETPOINT 50.0")
+        response = chamber.process("TEMP:ACTUAL?")
+
+        # Without physics engine, returns setpoint
+        assert response == "50.00"
+
+    def test_actual_as_command_fails(self, chamber: ThermalChamberSim) -> None:
+        """Test TEMP:ACTUAL (without ?) returns error."""
+        response = chamber.process("TEMP:ACTUAL 25.0")
+
+        assert response.startswith("ERROR:")
+        assert "query only" in response
+
+
+class TestThermalChamberStability:
+    """Tests for TEMP:STAB? query."""
+
+    @pytest.fixture
+    def chamber(self) -> ThermalChamberSim:
+        """Create chamber instance without physics engine."""
+        return ThermalChamberSim()
+
+    def test_stab_query_without_engine(self, chamber: ThermalChamberSim) -> None:
+        """Test TEMP:STAB? returns 1 when no physics engine."""
+        response = chamber.process("TEMP:STAB?")
+
+        # Without physics engine, assume stable
+        assert response == "1"
+
+    def test_stab_as_command_fails(self, chamber: ThermalChamberSim) -> None:
+        """Test TEMP:STAB (without ?) returns error."""
+        response = chamber.process("TEMP:STAB 1")
+
+        assert response.startswith("ERROR:")
+        assert "query only" in response
+
+
+class TestThermalChamberWithPhysicsEngine:
+    """Tests for ThermalChamberSim with physics engine integration."""
+
+    @pytest.fixture
+    def engine(self) -> PhysicsEngine:
+        """Create physics engine instance."""
+        return PhysicsEngine(update_rate_hz=100.0)
+
+    @pytest.fixture
+    def chamber(self, engine: PhysicsEngine) -> ThermalChamberSim:
+        """Create chamber instance with physics engine."""
+        return ThermalChamberSim(physics_engine=engine)
+
+    def test_setpoint_updates_engine(
+        self, chamber: ThermalChamberSim, engine: PhysicsEngine
+    ) -> None:
+        """Test TEMP:SETPOINT updates physics engine."""
+        chamber.process("TEMP:SETPOINT 85.0")
+
+        # Step the engine and check thermal state
+        thermal = engine.get_thermal_state()
+        # Initial chamber temp is 25, will start moving towards 85
+        assert thermal.chamber_temperature == pytest.approx(25.0, abs=0.1)
+
+        # After many steps, should approach setpoint
+        for _ in range(10000):  # 100 seconds at 100Hz
+            engine.step()
+
+        thermal = engine.get_thermal_state()
+        # Should be closer to setpoint (but not quite there due to time constant)
+        assert thermal.chamber_temperature > 80.0
+
+    def test_actual_query_returns_engine_temperature(
+        self, chamber: ThermalChamberSim, engine: PhysicsEngine
+    ) -> None:
+        """Test TEMP:ACTUAL? returns physics engine temperature."""
+        response = chamber.process("TEMP:ACTUAL?")
+
+        # Should match initial chamber temperature
+        assert response == "25.00"
+
+    def test_stability_when_at_setpoint(
+        self, chamber: ThermalChamberSim, engine: PhysicsEngine
+    ) -> None:
+        """Test TEMP:STAB? returns 1 when at setpoint."""
+        # Default setpoint is 25, engine starts at 25
+        response = chamber.process("TEMP:STAB?")
+
+        assert response == "1"
+
+    def test_stability_when_settling(
+        self, chamber: ThermalChamberSim, engine: PhysicsEngine
+    ) -> None:
+        """Test TEMP:STAB? returns 0 when settling."""
+        # Set new setpoint far from current temperature
+        chamber.process("TEMP:SETPOINT 85.0")
+
+        # Step once to ensure engine updates
+        engine.step()
+
+        # Should not be stable yet
+        response = chamber.process("TEMP:STAB?")
+        assert response == "0"
+
+    def test_reset_updates_engine(
+        self, chamber: ThermalChamberSim, engine: PhysicsEngine
+    ) -> None:
+        """Test *RST resets both chamber and engine setpoint."""
+        chamber.process("TEMP:SETPOINT 85.0")
+        chamber.process("*RST")
+
+        # Check setpoint is back to default
+        assert chamber.process("TEMP:SETPOINT?") == "25.00"

tests/unit/test_transport.py

@@ -0,0 +1,263 @@
+"""Unit tests for transport layer."""
+
+import socket
+from unittest.mock import MagicMock, Mock, patch
+
+import pytest
+
+from py_dvt_ate.instruments.transport.tcp import TCPTransport
+
+
+class TestTCPTransport:
+    """Tests for TCPTransport class."""
+
+    @pytest.fixture
+    def transport(self) -> TCPTransport:
+        """Create transport instance for tests."""
+        return TCPTransport("localhost", 5025, timeout=1.0)
+
+    def test_creation(self, transport: TCPTransport) -> None:
+        """Test TCPTransport can be created with valid parameters."""
+        assert transport.host == "localhost"
+        assert transport.port == 5025
+        assert not transport.is_connected
+
+    def test_repr(self, transport: TCPTransport) -> None:
+        """Test string representation."""
+        assert "localhost:5025" in repr(transport)
+        assert "disconnected" in repr(transport)
+
+    @patch("socket.socket")
+    def test_connect_success(
+        self, mock_socket_class: Mock, transport: TCPTransport
+    ) -> None:
+        """Test successful connection."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+
+        transport.connect()
+
+        assert transport.is_connected
+        mock_socket_class.assert_called_once_with(
+            socket.AF_INET, socket.SOCK_STREAM
+        )
+        mock_sock.settimeout.assert_called_once_with(1.0)
+        mock_sock.connect.assert_called_once_with(("localhost", 5025))
+
+    @patch("socket.socket")
+    def test_connect_already_connected(
+        self, mock_socket_class: Mock, transport: TCPTransport
+    ) -> None:
+        """Test connecting when already connected raises error."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+
+        transport.connect()
+
+        with pytest.raises(ConnectionError, match="Already connected"):
+            transport.connect()
+
+    @patch("socket.socket")
+    def test_connect_failure(
+        self, mock_socket_class: Mock, transport: TCPTransport
+    ) -> None:
+        """Test connection failure raises ConnectionError."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+        mock_sock.connect.side_effect = OSError("Connection refused")
+
+        with pytest.raises(ConnectionError, match="Failed to connect"):
+            transport.connect()
+
+        assert not transport.is_connected
+
+    @patch("socket.socket")
+    def test_disconnect(
+        self, mock_socket_class: Mock, transport: TCPTransport
+    ) -> None:
+        """Test disconnect closes socket."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+
+        transport.connect()
+        transport.disconnect()
+
+        mock_sock.close.assert_called_once()
+        assert not transport.is_connected
+
+    def test_disconnect_when_not_connected(self, transport: TCPTransport) -> None:
+        """Test disconnect is idempotent."""
+        transport.disconnect()  # Should not raise
+        assert not transport.is_connected
+
+    @patch("socket.socket")
+    def test_write(self, mock_socket_class: Mock, transport: TCPTransport) -> None:
+        """Test write sends command with newline."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+
+        transport.connect()
+        transport.write("*IDN?")
+
+        mock_sock.sendall.assert_called_once_with(b"*IDN?\n")
+
+    def test_write_not_connected(self, transport: TCPTransport) -> None:
+        """Test write when not connected raises error."""
+        with pytest.raises(ConnectionError, match="Not connected"):
+            transport.write("*IDN?")
+
+    @patch("socket.socket")
+    def test_write_failure(
+        self, mock_socket_class: Mock, transport: TCPTransport
+    ) -> None:
+        """Test write failure raises IOError."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+        mock_sock.sendall.side_effect = OSError("Write failed")
+
+        transport.connect()
+
+        with pytest.raises(OSError, match="Write failed"):
+            transport.write("*IDN?")
+
+    @patch("socket.socket")
+    def test_read(self, mock_socket_class: Mock, transport: TCPTransport) -> None:
+        """Test read receives response until newline."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+
+        # Simulate receiving "OK\n" byte by byte
+        mock_sock.recv.side_effect = [b"O", b"K", b"\n"]
+
+        transport.connect()
+        response = transport.read()
+
+        assert response == "OK"
+
+    @patch("socket.socket")
+    def test_read_with_timeout(
+        self, mock_socket_class: Mock, transport: TCPTransport
+    ) -> None:
+        """Test read with custom timeout."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+        mock_sock.gettimeout.return_value = 1.0
+
+        # Simulate receiving "OK\n"
+        mock_sock.recv.side_effect = [b"O", b"K", b"\n"]
+
+        transport.connect()
+        response = transport.read(timeout=2.0)
+
+        assert response == "OK"
+        # Verify timeout was changed and restored
+        assert mock_sock.settimeout.call_count == 3  # connect + custom + restore
+        mock_sock.settimeout.assert_any_call(2.0)
+        mock_sock.settimeout.assert_any_call(1.0)
+
+    def test_read_not_connected(self, transport: TCPTransport) -> None:
+        """Test read when not connected raises error."""
+        with pytest.raises(ConnectionError, match="Not connected"):
+            transport.read()
+
+    @patch("socket.socket")
+    def test_read_timeout(
+        self, mock_socket_class: Mock, transport: TCPTransport
+    ) -> None:
+        """Test read timeout raises TimeoutError."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+        mock_sock.recv.side_effect = TimeoutError("Timed out")
+
+        transport.connect()
+
+        with pytest.raises(TimeoutError, match="Read timeout"):
+            transport.read()
+
+    @patch("socket.socket")
+    def test_read_connection_closed(
+        self, mock_socket_class: Mock, transport: TCPTransport
+    ) -> None:
+        """Test read when connection closed raises error."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+        mock_sock.recv.return_value = b""  # Empty means connection closed
+
+        transport.connect()
+
+        with pytest.raises(ConnectionError, match="Connection closed"):
+            transport.read()
+
+    @patch("socket.socket")
+    def test_query(self, mock_socket_class: Mock, transport: TCPTransport) -> None:
+        """Test query combines write and read."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+
+        # Simulate receiving "Test Device\n"
+        mock_sock.recv.side_effect = [
+            b"T",
+            b"e",
+            b"s",
+            b"t",
+            b" ",
+            b"D",
+            b"e",
+            b"v",
+            b"i",
+            b"c",
+            b"e",
+            b"\n",
+        ]
+
+        transport.connect()
+        response = transport.query("*IDN?")
+
+        assert response == "Test Device"
+        mock_sock.sendall.assert_called_once_with(b"*IDN?\n")
+
+    @patch("socket.socket")
+    def test_query_with_timeout(
+        self, mock_socket_class: Mock, transport: TCPTransport
+    ) -> None:
+        """Test query with custom timeout."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+        mock_sock.gettimeout.return_value = 1.0
+
+        mock_sock.recv.side_effect = [b"O", b"K", b"\n"]
+
+        transport.connect()
+        response = transport.query("*IDN?", timeout=3.0)
+
+        assert response == "OK"
+        mock_sock.settimeout.assert_any_call(3.0)
+
+    @patch("socket.socket")
+    def test_context_manager(
+        self, mock_socket_class: Mock, transport: TCPTransport
+    ) -> None:
+        """Test context manager connects and disconnects."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+
+        with transport:
+            assert transport.is_connected
+
+        mock_sock.close.assert_called_once()
+        assert not transport.is_connected
+
+    @patch("socket.socket")
+    def test_context_manager_with_exception(
+        self, mock_socket_class: Mock, transport: TCPTransport
+    ) -> None:
+        """Test context manager disconnects even on exception."""
+        mock_sock = MagicMock()
+        mock_socket_class.return_value = mock_sock
+
+        with pytest.raises(ValueError):
+            with transport:
+                raise ValueError("Test error")
+
+        mock_sock.close.assert_called_once()
+        assert not transport.is_connected