docs(examples): add chatbot testing example

Demonstrates pytest integration for chatbot QA with validate_text()
assertions, fixtures, and parametrised content safety tests.

examples/chatbot_testing.py

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+"""Pytest integration for chatbot testing.
+
+Demonstrates Veritext's pytest plugin for testing chatbot responses:
+- validate_text() assertion function
+- Custom test fixtures
+- Test organisation with markers
+"""
+
+import pytest
+
+from veritext.pytest_plugin import validate_text
+
+# Sample chatbot responses for testing
+CHATBOT_RESPONSES = {
+    "greeting": {
+        "input": "Hello!",
+        "response": "Hi there! How can I help you today?",
+        "expected_keywords": ["help", "hi"],
+    },
+    "weather": {
+        "input": "What's the weather like?",
+        "response": "I don't have access to real-time weather data, but you can "
+        "check a weather service like weather.com for current conditions.",
+        "expected_keywords": ["weather", "check"],
+    },
+    "farewell": {
+        "input": "Goodbye!",
+        "response": "Goodbye! Have a great day!",
+        "expected_keywords": ["goodbye", "day"],
+    },
+}
+
+
+# Fixtures for common test setup
+@pytest.fixture
+def greeting_response() -> str:
+    """Provide a sample greeting response."""
+    return CHATBOT_RESPONSES["greeting"]["response"]
+
+
+@pytest.fixture
+def weather_response() -> str:
+    """Provide a sample weather response."""
+    return CHATBOT_RESPONSES["weather"]["response"]
+
+
+# Basic validation tests
+class TestResponseQuality:
+    """Test chatbot response quality using Veritext."""
+
+    def test_greeting_length(self, greeting_response: str) -> None:
+        """Greeting responses should be concise."""
+        validate_text(
+            greeting_response,
+            min_length=10,
+            max_length=100,
+        )
+
+    def test_greeting_readability(self, greeting_response: str) -> None:
+        """Greeting responses should be easy to read."""
+        validate_text(
+            greeting_response,
+            max_reading_grade=8.0,
+        )
+
+    def test_greeting_contains_keywords(self, greeting_response: str) -> None:
+        """Greeting should contain expected terms."""
+        validate_text(
+            greeting_response,
+            must_contain=["help"],
+        )
+
+    def test_weather_response_quality(self, weather_response: str) -> None:
+        """Weather response should be informative and readable."""
+        validate_text(
+            weather_response,
+            min_length=50,
+            max_length=500,
+            max_reading_grade=10.0,
+            must_contain=["weather"],
+        )
+
+
+# Tests with reference comparison
+class TestResponseSimilarity:
+    """Test response similarity against reference texts."""
+
+    def test_greeting_similarity(self) -> None:
+        """Greeting should match expected style."""
+        reference = "Hello! How may I assist you today?"
+        response = CHATBOT_RESPONSES["greeting"]["response"]
+
+        validate_text(
+            response,
+            reference=reference,
+            min_rouge=0.3,  # Allow variation in wording
+            min_length=10,
+        )
+
+    def test_farewell_similarity(self) -> None:
+        """Farewell should match expected style."""
+        reference = "Goodbye! Have a wonderful day!"
+        response = CHATBOT_RESPONSES["farewell"]["response"]
+
+        validate_text(
+            response,
+            reference=reference,
+            min_rouge=0.5,
+            must_contain=["goodbye"],
+        )
+
+
+# Content safety tests
+class TestContentSafety:
+    """Test responses for inappropriate content."""
+
+    @pytest.mark.parametrize("response_key", ["greeting", "weather", "farewell"])
+    def test_no_profanity(self, response_key: str) -> None:
+        """Responses should not contain profanity."""
+        response = CHATBOT_RESPONSES[response_key]["response"]
+        validate_text(
+            response,
+            must_exclude=["damn", "hell", "crap"],
+            min_length=1,
+        )
+
+    @pytest.mark.parametrize("response_key", ["greeting", "weather", "farewell"])
+    def test_no_harmful_content(self, response_key: str) -> None:
+        """Responses should not contain harmful instructions."""
+        response = CHATBOT_RESPONSES[response_key]["response"]
+        validate_text(
+            response,
+            must_exclude=["hack", "exploit", "attack"],
+            min_length=1,
+        )
+
+
+# Run tests when executed directly
+if __name__ == "__main__":
+    pytest.main([__file__, "-v"])