feat: Set up comprehensive Python testing infrastructure with Poetry

[llbbl]

Set Up Python Testing Infrastructure

Summary

This PR establishes a comprehensive testing infrastructure for the drymail project using Poetry as the package manager and pytest as the testing framework.

Changes Made

Package Management

• Migrated to Poetry: Created pyproject.toml with all project metadata and dependencies
• Preserved existing dependencies: Migrated mistune and beautifulsoup4 from requirements.txt
• Added development dependencies:
  • pytest - Core testing framework
  • pytest-cov - Coverage reporting plugin
  • pytest-mock - Mocking utilities

Testing Configuration

• Pytest configuration in pyproject.toml:

  • Test discovery patterns for test_*.py and *_test.py files
  • Strict markers and configuration
  • Coverage reporting with 80% threshold
  • Output formats: terminal, HTML, and XML reports
  • Custom markers: unit, integration, and slow

• Coverage configuration:

  • Source set to drymail module
  • Exclusions for test files and common patterns
  • Branch coverage enabled

Directory Structure

tests/
├── __init__.py
├── conftest.py
├── test_infrastructure_validation.py
├── unit/
│   └── __init__.py
└── integration/
    └── __init__.py

Shared Fixtures (conftest.py)

• temp_dir - Temporary directory for test files
• mock_smtp_server - Mock SMTP server for email testing
• mock_email_config - Sample email configuration
• sample_email_data - Test email data
• mock_attachment - File attachment mock
• temp_file - Helper to create temporary files
• reset_environment - Auto-cleanup of environment variables
• capture_logs - Log capture utility

Additional Updates

• Updated .gitignore with:
  • Testing artifacts (.pytest_cache/, coverage files)
  • Claude settings (.claude/*)
  • IDE and OS files
  • Note: poetry.lock is NOT ignored (as per best practices)

How to Use

Install Dependencies

# Install Poetry (if not already installed)
curl -sSL https://install.python-poetry.org | python3 -

# Install project dependencies
poetry install

Running Tests

# Run all tests
poetry run test
# or
poetry run tests

# Run with specific markers
poetry run pytest -m unit
poetry run pytest -m integration
poetry run pytest -m "not slow"

# Run with coverage report
poetry run pytest --cov-report=html
# Coverage report will be in htmlcov/index.html

Writing Tests

1. Place unit tests in tests/unit/
2. Place integration tests in tests/integration/
3. Use the provided fixtures from conftest.py
4. Mark tests appropriately: @pytest.mark.unit, @pytest.mark.integration, @pytest.mark.slow

Notes

• The coverage threshold is set to 80%. Tests will fail if coverage drops below this
• The existing requirements.txt and setup.py are preserved for backward compatibility
• Poetry will create a virtual environment in .venv/ automatically
• All pytest standard options are available when running tests

Validation

The infrastructure has been validated with a comprehensive test suite (test_infrastructure_validation.py) that verifies:

• Basic pytest functionality
• All fixtures are accessible and working
• Markers are properly configured
• Mocking capabilities work
• Coverage tracking is functional
• Parametrized tests work correctly