feat: Set up comprehensive Python testing infrastructure with Poetry

[llbbl]

Set up Python Testing Infrastructure with Poetry

Summary

This PR establishes a comprehensive testing infrastructure for the sketchpy3 project, migrating from setup.py to Poetry for dependency management and creating a complete testing environment ready for development.

Changes Made

Package Management

• ✅ Created pyproject.toml with Poetry configuration
• ✅ Migrated dependencies from setup.py to Poetry format
• ✅ Removed turtle dependency (built-in Python module)
• ✅ Added testing dependencies: pytest, pytest-cov, pytest-mock as dev dependencies

Testing Configuration

• ✅ pytest configuration with custom markers (unit, integration, slow)
• ✅ Coverage settings with 80% threshold requirement
• ✅ HTML and XML coverage reports generation
• ✅ Strict configuration for consistent test execution

Directory Structure

tests/
├── __init__.py
├── conftest.py              # Shared fixtures and test utilities
├── test_setup_validation.py # Infrastructure validation tests
├── unit/
│   └── __init__.py
└── integration/
    └── __init__.py

Testing Fixtures & Utilities

• ✅ Comprehensive conftest.py with fixtures for:
  • Temporary directories and files
  • Mock objects for turtle, OpenCV, requests, multiprocessing
  • Sample data generators (coordinates, SVG data)
  • Environment variable management
  • Automatic test cleanup

Development Environment

• ✅ Updated .gitignore with testing artifacts, IDE files, and environment entries
• ✅ Poetry lock file generated and dependencies installed
• ✅ Validation tests to verify infrastructure functionality

How to Use

Running Tests

# Run all tests
poetry run python -m pytest

# Run with coverage
poetry run python -m pytest --cov=sketchpy3

# Run only unit tests
poetry run python -m pytest -m unit

# Run only integration tests  
poetry run python -m pytest -m integration

# Run validation tests
poetry run python -m pytest tests/test_setup_validation.py

Installing Dependencies

# Install all dependencies (production + development)
poetry install

# Install only production dependencies
poetry install --only main

Coverage Reports

• Terminal: Coverage summary displayed after test runs
• HTML: Generated in htmlcov/ directory - open htmlcov/index.html
• XML: Generated as coverage.xml for CI/CD integration

Testing Infrastructure Features

Custom pytest Markers

• @pytest.mark.unit - Fast, isolated unit tests
• @pytest.mark.integration - Integration tests with external dependencies
• @pytest.mark.slow - Long-running tests

Available Fixtures

• temp_dir, temp_file - Temporary file system fixtures
• mock_turtle, mock_cv2, mock_requests - Mock external dependencies
• sample_coordinates, sample_svg_data - Test data generators
• mock_config, environment_vars - Configuration and environment setup

Quality Assurance

• 80% coverage threshold - Tests must maintain high coverage
• Strict markers - Prevents typos in test markers
• Automatic cleanup - Test artifacts are cleaned up automatically
• Cross-platform compatibility - Works on Windows, macOS, Linux

Notes

• The infrastructure is ready for developers to start writing tests immediately
• All dependencies have been successfully installed and verified
• Validation tests confirm the testing environment is working correctly
• Legacy setup.py remains for backward compatibility but Poetry is now the primary package manager
• No actual unit tests for the codebase were written - only infrastructure setup and validation

Next Steps for Developers

1. Write unit tests in tests/unit/ for individual functions and classes
2. Write integration tests in tests/integration/ for component interactions
3. Use existing fixtures from conftest.py to mock dependencies
4. Run tests frequently during development with poetry run python -m pytest
5. Check coverage to ensure comprehensive testing

🚀 The testing infrastructure is now ready for development!