feat: Set up comprehensive Python testing infrastructure with Poetry

[llbbl]

Python Testing Infrastructure Setup

Summary

This PR establishes a complete testing infrastructure for the Python project using Poetry as the package manager. The setup provides a robust foundation for test-driven development with comprehensive tooling and configuration.

Changes Made

Package Management

• ✅ Configured Poetry as the package manager (already present in pyproject.toml)
• ✅ Added testing dependencies as development dependencies:
  • pytest (^8.3.4) - Core testing framework
  • pytest-cov (^6.0.0) - Coverage reporting plugin
  • pytest-mock (^3.14.0) - Mocking utilities

Testing Configuration

• ✅ Added comprehensive pytest configuration in pyproject.toml:

  • Test discovery patterns for flexible test file naming
  • Coverage reporting with HTML and XML output formats
  • Custom markers for test categorization (unit, integration, slow)
  • Strict mode settings for better test quality

• ✅ Added coverage configuration:

  • Source code coverage tracking
  • Exclusion patterns for non-test code
  • Branch coverage enabled
  • Multiple report formats (terminal, HTML, XML)

Directory Structure

tests/
├── __init__.py
├── conftest.py                    # Shared fixtures and configuration
├── test_infrastructure_validation.py  # Validation tests
├── unit/
│   └── __init__.py
└── integration/
    └── __init__.py

Shared Fixtures

Created comprehensive fixtures in conftest.py:

• File System: temp_dir, temp_file, mock_json_file
• Configuration: mock_config, mock_environment_variables
• Mocking: mock_api_client, mock_database_connection, mock_requests
• Testing Utilities: performance_timer, captured_logs, mock_datetime
• Data: sample_data with users, products, and orders

Validation Tests

Added 26 validation tests to verify:

• All testing dependencies are properly installed
• Python version meets requirements (>=3.11)
• Directory structure is correctly set up
• All fixtures work as expected
• Custom markers can be applied
• Mocking capabilities function properly

Version Control

Created .gitignore with comprehensive patterns for:

• Python artifacts (__pycache__, *.pyc, etc.)
• Testing artifacts (.pytest_cache, .coverage, htmlcov/)
• Virtual environments
• IDE files
• Claude-specific settings (.claude/)

How to Use

Running Tests

# Run all tests with coverage
poetry run pytest

# Run specific test categories
poetry run pytest -m unit          # Run unit tests only
poetry run pytest -m integration   # Run integration tests only
poetry run pytest -m "not slow"    # Skip slow tests

# Run tests for specific files/directories
poetry run pytest tests/unit/
poetry run pytest tests/test_infrastructure_validation.py

# Run with specific output options
poetry run pytest -v               # Verbose output
poetry run pytest --tb=short       # Short traceback format

Coverage Reports

After running tests, coverage reports are available in:

• Terminal: Shown automatically after test run
• HTML: Open htmlcov/index.html in a browser
• XML: coverage.xml for CI/CD integration

Writing New Tests

1. Place unit tests in tests/unit/

2. Place integration tests in tests/integration/

3. Use appropriate markers:

   @pytest.mark.unit
   def test_something():
       pass
   
   @pytest.mark.integration
   def test_api_integration():
       pass
   
   @pytest.mark.slow
   def test_long_running_process():
       pass
   

4. Utilize shared fixtures from conftest.py:

   def test_with_temp_file(temp_file):
       assert temp_file.exists()
       content = temp_file.read_text()
       # ... test logic
   

Dependencies Note

• Poetry lock file has been updated to include new testing dependencies
• All dependencies are installed in the development group (not production)
• The project uses Python 3.11+ as specified in pyproject.toml

Validation

✅ All 26 validation tests pass successfully ✅ Testing infrastructure is fully operational ✅ Coverage reporting is configured (currently set to 0% threshold for initial setup)

Next Steps

1. Developers can immediately start writing unit and integration tests
2. Coverage threshold can be increased as more tests are added
3. CI/CD pipeline can use the XML coverage report for integration
4. Additional test fixtures can be added to conftest.py as needed