How to use Ruff, Mypy, Black, Isort and Pytest in GitHub Actions?

Python’s not the strictest language, so to have any confidence in your code it needs to be hit with a barrage of checks to ensure it meets some level of quality.

I use the following code quality checks:

• Ruff for linting
• Mypy for type checking
• Black to ensure code is formatted
• Isort to ensure imports are grouped and sorted

The following Github Actions workflow will check your code when a pull request is created, catching problems before they’re merged.

How to add the Github Actions workflow

Add the following to your repository in .github/workflows/code-quality.yml.

name: Code Quality
on: [pull_request]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
    - uses: actions/setup-python@v2
      with:
        python-version: "3.7"
    - run: pip install --upgrade pip
    - run: pip install "ruff<1" "mypy<2" "black<23" "isort<6" pytest
    - run: ruff check .
    - run: mypy --strict .
    - run: black --check .
    - run: isort --check --profile black .
    - run: pytest .

Notes

• To exclude certain files and directories, use the exclude options to each tool, (usually --exclude).
• If you have an existing project with unformatted code, format the entire project all at once. Don’t do it gradually. I do it in a single dedicated PR, but I’ve seen others reformat the repository’s entire history, to preserve git blame.

See also: How to use Ruff, Mypy, Black and Isort in Pre-commit?