From 822e74c1aa3c832eb59c04eb323669a65f812ed4 Mon Sep 17 00:00:00 2001
From: Kai Chappell <git@kschappell.com>
Date: Wed, 25 Jun 2025 19:25:42 +0000
Subject: [PATCH] Refactor Transport from Protocol to ABC for explicit
 interface implementation

---
 src/py_dvt_ate/instruments/transport/base.py | 34 +++++++++++++-------
 src/py_dvt_ate/instruments/transport/tcp.py  |  6 ++--
 2 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/src/py_dvt_ate/instruments/transport/base.py b/src/py_dvt_ate/instruments/transport/base.py
index 7cb2e87..0538114 100644
--- a/src/py_dvt_ate/instruments/transport/base.py
+++ b/src/py_dvt_ate/instruments/transport/base.py
@@ -1,31 +1,38 @@
-"""Base transport protocol for instrument communication."""
+"""Base transport interface for instrument communication."""
 
-from typing import Protocol
+from abc import ABC, abstractmethod
 
 
-class Transport(Protocol):
+class Transport(ABC):
     """Abstract transport interface for instrument communication.
 
-    This protocol defines the interface that all transport implementations
-    (TCP, VISA, etc.) must satisfy. It provides basic connection management
-    and communication primitives for SCPI-based instruments.
+    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.
 
@@ -36,8 +43,9 @@ class Transport(Protocol):
             ConnectionError: If not connected.
             IOError: If write fails.
         """
-        ...
+        pass
 
+    @abstractmethod
     def read(self, timeout: float | None = None) -> str:
         """Read response from instrument.
 
@@ -52,8 +60,9 @@ class Transport(Protocol):
             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.
 
@@ -71,13 +80,14 @@ class Transport(Protocol):
             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
diff --git a/src/py_dvt_ate/instruments/transport/tcp.py b/src/py_dvt_ate/instruments/transport/tcp.py
index 32b82f0..342b75d 100644
--- a/src/py_dvt_ate/instruments/transport/tcp.py
+++ b/src/py_dvt_ate/instruments/transport/tcp.py
@@ -3,11 +3,13 @@
 import socket
 from typing import Any
 
+from py_dvt_ate.instruments.transport.base import Transport
 
-class TCPTransport:
+
+class TCPTransport(Transport):
     """TCP socket transport implementation.
 
-    Implements the Transport protocol for communicating with SCPI
+    Implements the Transport interface for communicating with SCPI
     instruments over TCP/IP using newline-terminated messages.
 
     Attributes: