feat: Set up comprehensive Python testing infrastructure

[llbbl]

Set up Python Testing Infrastructure

Summary

This PR establishes a comprehensive testing infrastructure for the FLUX training project, providing a complete foundation for writing and running tests.

Changes Made

Package Management

• Poetry Setup: Created pyproject.toml with Poetry configuration
• Dependency Migration: Migrated all dependencies from requirements.txt to Poetry format
• Python Version: Updated to require Python 3.10+ to support all dependencies
• Test Dependencies: Added pytest, pytest-cov, and pytest-mock as development dependencies

Testing Configuration

• Pytest Configuration: Comprehensive pytest setup in pyproject.toml including:
  • Test discovery patterns for files, classes, and functions
  • Coverage reporting with 80% threshold
  • HTML and XML coverage output formats
  • Custom markers for unit, integration, and slow tests
  • Strict configuration and warning handling
• Coverage Settings: Configured to exclude test files, build artifacts, and virtual environments

Directory Structure

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

Shared Fixtures (conftest.py)

• temp_dir: Temporary directory for file operations
• mock_torch_device: Mock PyTorch device for CPU-only testing
• mock_model_config / mock_training_config: Configuration mocks
• sample_data: Sample data for testing ML components
• mock_wandb: Mock W&B logging for testing
• mock_transformers / mock_diffusers: Mock ML model components
• disable_gpu: Automatically disable GPU for all tests
• File operation mocks: Mock file system operations

Infrastructure Validation

• Validation Test Suite: test_setup_validation.py verifies:
  • Pytest functionality
  • Python version compatibility
  • Project structure integrity
  • Fixture availability and functionality
  • Test markers working correctly
  • Import capabilities

Configuration Updates

• .gitignore: Added Claude Code settings exclusion
• Lock Files: Poetry.lock is tracked (not excluded) for reproducible builds

Running Tests

Install Dependencies

poetry install

Run Tests

# Run all tests
poetry run pytest

# Run with verbose output
poetry run pytest -v

# Run specific test file
poetry run pytest tests/test_setup_validation.py

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

Coverage Reports

• Terminal: Coverage summary displayed after test runs
• HTML: Available in htmlcov/index.html
• XML: Available in coverage.xml for CI systems

Notes

• No Production Code Tests: This PR only sets up the infrastructure - no actual unit tests for the ML codebase are included yet
• Ready for Development: Developers can now immediately start writing tests using the provided fixtures and structure
• CI/CD Ready: Coverage reporting formats are compatible with most CI systems
• Extensible: Easy to add more fixtures and test categories as needed

Validation

✅ Dependencies install successfully
✅ All validation tests pass (10/10)
✅ Coverage reporting generates correctly
✅ Test discovery finds validation tests
✅ Fixtures work as expected
✅ Markers are properly configured