feat: Set up comprehensive Python testing infrastructure

[llbbl]

Set up comprehensive Python testing infrastructure

Summary

This PR establishes a complete testing infrastructure for the ChopHound project, providing developers with a robust foundation for writing and running tests.

Changes Made

Package Management

• Added Poetry as the package manager with comprehensive pyproject.toml configuration
• Migrated dependencies from implicit imports to explicit Poetry dependency management
• Set up development dependencies for testing tools

Testing Framework

• Installed pytest as the main testing framework with advanced configuration
• Added pytest-cov for comprehensive coverage reporting (HTML, XML, terminal)
• Added pytest-mock for powerful mocking capabilities in tests
• Configured custom markers (unit, integration, slow) for test categorization

Project Structure

• Created testing directories: tests/, tests/unit/, tests/integration/
• Added comprehensive fixtures in tests/conftest.py including:
  • Temporary directory management
  • Sample JSON file creation for testing
  • Mock argument helpers
  • Environment cleanup utilities
• Created validation tests to ensure infrastructure works correctly

Configuration

• Pytest settings: Strict configuration, coverage thresholds, test discovery patterns
• Coverage configuration: Source mapping, exclusion patterns, reporting formats
• Updated .gitignore: Added testing artifacts, Python build files, IDE files

Testing Commands

Developers can now run tests using:

# Install dependencies
poetry install

# Run all tests
poetry run pytest

# Run tests with verbose output
poetry run pytest -v

# Run only unit tests
poetry run pytest -m unit

# Run only integration tests  
poetry run pytest -m integration

# Skip slow tests
poetry run pytest -m "not slow"

# Generate coverage report
poetry run pytest --cov=. --cov-report=html

Validation

• ✅ All infrastructure tests pass
• ✅ Coverage reporting generates HTML and XML outputs
• ✅ Poetry dependency management works correctly
• ✅ Custom pytest markers function properly
• ✅ Shared fixtures are available across test modules

Dependencies Added

• pytest ^7.4.0 - Main testing framework
• pytest-cov ^4.1.0 - Coverage reporting
• pytest-mock ^3.11.1 - Mocking utilities
• ijson ^3.2.3 - JSON parsing (existing dependency, now managed by Poetry)

Notes for Developers

• The testing infrastructure is ready for immediate use
• Coverage threshold is currently set to 0% to allow gradual adoption
• Shared fixtures in conftest.py provide common testing utilities
• Both tests/unit/ and tests/integration/ directories are ready for test files
• The poetry.lock file should be committed to ensure reproducible builds