feat: set up Python testing infrastructure with Poetry and pytest

[llbbl]

Set Up Python Testing Infrastructure

Summary

This PR establishes a complete testing infrastructure for the ML Interpretability Papers project using Poetry as the package manager and pytest as the testing framework.

Changes Made

Package Management

• Initialized Poetry as the package manager with pyproject.toml configuration
• Added project metadata and package configuration for the sbin module

Testing Dependencies

Added the following development dependencies:

• pytest (^8.0.0) - Core testing framework
• pytest-cov (^5.0.0) - Coverage reporting plugin
• pytest-mock (^3.14.0) - Mocking utilities

Testing Configuration

• Configured pytest in pyproject.toml with:
  • Test discovery patterns for test_*.py and *_test.py files
  • Custom markers: unit, integration, and slow
  • Strict mode for markers and configuration
• Added .coveragerc for detailed coverage configuration:
  • 80% coverage threshold (commented out for initial setup)
  • HTML and XML report generation
  • Exclusion patterns for non-testable code

Directory Structure

Created organized testing structure:

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

Fixtures and Configuration

Added comprehensive fixtures in conftest.py:

• temp_dir - Temporary directory for testing
• sample_cache_data - Sample data for cache testing
• sample_cache_file - Test cache file creation
• sample_readme_template - Test template file
• mock_http_response - HTTP response mocking helper
• mock_env_vars - Environment variable management
• isolated_filesystem - Isolated test environment

Development Commands

Configured Poetry scripts for consistent test execution:

• poetry run test - Run all tests
• poetry run tests - Alternative command (both work)

Additional Setup

• Updated .gitignore with comprehensive Python, testing, and Claude-specific entries
• Added sbin/__init__.py to make it a proper Python package
• Created validation tests to verify the infrastructure works correctly

How to Use

1. Install dependencies:

   poetry install

2. Run tests:

   # Run all tests
   poetry run test
   
   # Run with coverage
   poetry run pytest --cov=sbin --cov-report=html
   
   # Run specific test markers
   poetry run pytest -m unit
   poetry run pytest -m integration

3. Write new tests:

   • Unit tests go in tests/unit/
   • Integration tests go in tests/integration/
   • Use fixtures from conftest.py for common test needs
   • Mark tests appropriately with @pytest.mark.unit, etc.

Notes

• The coverage threshold is currently commented out in .coveragerc since no actual code tests exist yet
• The validation tests confirm that all testing infrastructure is properly installed and configured
• Poetry lock file is tracked in git for reproducible environments
• All pytest options and plugins are available for use