para-pytest 0.1.2

Run pytest tests in parallel chunks for faster test execution

Parallel Pytest (para-pytest)

Run pytest tests in parallel chunks for significantly faster test execution.

Installation

pip install para-pytest

Quick Start

# Run with default settings (4 chunks)
para-pytest

# Specify number of chunks
para-pytest --chunks 8

# Specify test path
para-pytest --path tests/

CLI Options

para-pytest [OPTIONS]

Options:
  --chunks N      Number of parallel chunks (default: 4)
  --path PATH     Path to tests (default: current directory)
  --debug         Show detailed chunking and pattern matching info

Useful for debugging:

# See which tests match serial patterns and how tests are chunked
para-pytest --path tests/ --debug

Use Cases

Local Development

Speed up your test suite during development:

# Before (sequential execution)
pytest tests/

# After (parallel execution)
para-pytest --chunks 4

Continuous Integration

Add to your GitHub Actions workflow:

name: Tests

on: [push, pull_request]

jobs: 
	test:
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4

      - uses: actions/setup-python@v5
        with:
          python-version: '3.12.3'

      - name: Install dependencies
        run: |
          pip install -r requirements.txt
          pip install para-pytest

      - name: Run tests
        run: para-pytest --chunks 4 --path tests/

Or use the Github Action:

- uses: ALHelton/parallel-pytest@v1
  with:
    chunks: 8
    path: tests/

Python API

from para_pytest import ParaPytestRunner

# Serial patterns are automatically loaded from pyproject.toml
runner = ParaPytestRunner(chunks=4, pytest_args=['tests/'])
exit_code = runner.run()

# Or explicitly pass serial patterns (overrides pyproject.toml)
runner = ParaPytestRunner(
    chunks=4,
    pytest_args=['tests/'],
    serial_patterns=['**/test_database_*', '**/test_integration_*']
)
exit_code = runner.run()

Configuration (Optional)

Serial Test Patterns

Some tests can't run in parallel (e.g., database tests, integration tests with shared state). Configure these to run serially by adding to your existing pyproject.toml:

[tool.para-pytest]
serial_patterns = [
    "**/test_database_*",
    "**/test_migration_*",
    "**/test_integration_*",
    "tests/e2e/**"
]

Pattern examples:

• **/test_database_* - Any test file starting with test_database_ anywhere in your project
• tests/e2e/** - All tests in the tests/e2e/ directory and subdirectories
• **/test_*_integration.py - Any test file ending with _integration.py

That's it! No external dependencies required - the configuration is parsed using built-in Python modules.

Performance

Real-world example with 2000+ tests:

Method	Time	Speedup
pytest tests/	50s	1x
para-pytest --chunks 4	15s	3.3x
para-pytest --chunks 8	10s	5x

Performance varies based on test suite characteristics

How It Works

1. Loads serial patterns from pyproject.toml (if configured)
2. Collects all tests from pytest
3. Separates tests into parallel and serial groups based on patterns
4. Splits parallel tests into equal chunks
5. Runs parallel chunks concurrently using asyncio
6. Runs serial tests sequentially (if any)
7. Aggregates and displays results

Troubleshooting

Tests Fail in Parallel But Pass Normally?

Some tests can't run in parallel due to shared state (databases, files, etc.). Configure them to run serially:

[tool.para-pytest]
serial_patterns = [
    "**/test_database_*",
    "**/test_integration_*",
]

Run with --debug to see which tests are being run serially:

para-pytest --path tests/ --debug

Common Patterns for Serial Tests

• Database tests: **/test_database_*, **/test_migration_*
• Integration tests: **/test_integration_*, tests/integration/**
• E2E tests: tests/e2e/**, tests/functional/**
• Any test modifying shared resources

Requirements

• Python 3.8+
• pytest 7.0+

License

MIT