Add comprehensive Python testing infrastructure

[llbbl]

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About UnitSeeker

Hi! This PR is part of the UnitSeeker project, a human-guided initiative to help Python repositories establish testing infrastructure.

Key points:

• Human-approved: Every PR is manually approved before work begins
• Semi-automated with oversight: Created and controlled via a homegrown wrapper around Claude Code with human quality control
• Infrastructure only: This PR intentionally contains only the testing setup without actual unit tests
• Your repository, your rules: Feel free to modify, reject, or request changes - all constructive feedback is welcome
• Follow-up support: All responses and discussions are personally written, not automated

Learn more about the project and see the stats on our progress at https://unitseeker.llbbl.com/

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Summary

This PR adds a comprehensive testing infrastructure to the StarCoder project, providing a foundation for writing and running tests with minimal friction.

Changes Made

Package Management

• Poetry Setup: Migrated from requirements.txt to Poetry for modern Python dependency management
• Dependency Migration: All existing dependencies from requirements.txt preserved in pyproject.toml
• Testing Dependencies: Added pytest, pytest-cov, and pytest-mock as development dependencies
• Lock File: Generated poetry.lock for reproducible builds across environments

Testing Configuration

• pytest Configuration: Comprehensive pytest setup in pyproject.toml with:
  • Test discovery patterns for files, classes, and functions
  • Coverage tracking for chat/ and finetune/ packages
  • HTML, XML, and terminal coverage reporting
  • Strict markers and config enforcement
  • Custom markers: @pytest.mark.unit, @pytest.mark.integration, @pytest.mark.slow
  • Coverage threshold placeholder (80%) ready to be enabled

Directory Structure

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

Shared Test Fixtures

The tests/conftest.py file provides reusable fixtures for common testing scenarios:

• temp_dir - Temporary directory for file operations
• temp_file - Temporary test file
• mock_config - Mock configuration dictionary
• mock_tokenizer - Mock HuggingFace tokenizer
• mock_model - Mock model for inference testing
• sample_text & sample_code_snippet - Sample data
• mock_dataset - Mock dataset for data pipeline testing
• mock_training_args - Mock training configuration
• mock_huggingface_hub - Mock HuggingFace Hub client
• reset_environment - Auto-cleanup for environment variables

Validation Tests

Created test_infrastructure.py with 27 tests to validate:

• ✅ pytest is working correctly
• ✅ Python version requirements (3.8+)
• ✅ Project structure is correct
• ✅ Custom markers are registered and functional
• ✅ All fixtures work as expected
• ✅ Coverage and mocking packages are installed
• ✅ Test parametrization works

Development Commands

Two convenient shortcuts for running tests:

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

Updated .gitignore

Added entries for:

• Claude Code artifacts (.claude/)
• VS Code settings (.vscode/, *.code-workspace)
• Testing artifacts already covered by default Python gitignore

Running Tests

Setup

# Install dependencies (first time only)
poetry install

# Run all tests
poetry run pytest

# Run 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

# Run tests without coverage
poetry run pytest --no-cov

# Generate and view coverage report
poetry run pytest
open htmlcov/index.html  # View HTML coverage report

Using the shortcuts

poetry run test      # Runs pytest with all configured options
poetry run tests     # Alternative (same as above)

Notes

Coverage Threshold

The 80% coverage threshold is currently commented out in pyproject.toml:

# Uncomment to enforce coverage threshold once actual tests are written:
# "--cov-fail-under=80",

Uncomment this line when you're ready to enforce minimum coverage requirements.

No Actual Unit Tests

This PR intentionally does not include unit tests for the codebase. The goal is to provide:

1. A working testing infrastructure
2. Validated configuration
3. Useful fixtures and examples
4. Clear documentation

Developers can immediately start writing tests without any setup overhead.

Poetry vs pip

Poetry was chosen for:

• Modern dependency resolution
• Automatic virtual environment management
• Lockfile for reproducible builds
• Built-in support for dev dependencies
• Simple script shortcuts

If you prefer to stick with requirements.txt, you can extract dependencies:

poetry export -f requirements.txt --output requirements.txt

Dependencies

All existing dependencies preserved:

• tqdm==4.65.0
• transformers==4.28.1
• datasets==2.11.0
• huggingface-hub==0.13.4
• accelerate==0.18.0

Testing the Infrastructure

The infrastructure has been validated with 27 passing tests:

============================= 27 passed in 0.28s =============================

All features confirmed working:

• ✅ Test discovery and execution
• ✅ Coverage reporting (HTML, XML, terminal)
• ✅ Custom markers
• ✅ All fixtures
• ✅ Test parametrization
• ✅ Mocking capabilities

Next Steps

1. Start Writing Tests: Use the fixtures in conftest.py as building blocks
2. Organize Tests: Place unit tests in tests/unit/, integration tests in tests/integration/
3. Use Markers: Tag tests with @pytest.mark.unit, @pytest.mark.integration, or @pytest.mark.slow
4. Enable Coverage Threshold: Uncomment --cov-fail-under=80 when ready
5. Customize: Modify pyproject.toml settings to match your team's preferences

Questions?

Feel free to ask questions, request changes, or suggest improvements. All feedback is welcome and appreciated!