Here are some common patterns in development workflows, and how to best achieve them with thx.

Version Matrix

thx has direct support for running jobs on multiple Python versions in parallel. Projects only need to list the set of supported Python versions, and thx will make a best effort to find and run jobs on as many of these versions as possible:

python_versions = ["3.8", "3.9", "3.10", "3.11"]


Formatters should generally only be run once, to prevent race conditions between jobs on multiple Python versions running in parallel. Setting once = true will make sure your formatter only gets run on the latest enabled Python version:

run = ["black {module}"]
once = true


When running linters, results are often independent from each other, and it is often unnecessary to wait for other steps to finish first before the next one starts. Recommended practice is to combine all linters into a single parallel job, to make best use of multi-core systems:

run = [
    "black --check {module}",
    "flake8 {module}",
    "mypy -p {module}",
parallel = true

Test Coverage

Recording and collecting test coverage data must be handled carefully when running tests in parallel across multiple Python versions. Recommended practice is to enable parallel support in your coverage configuration, and add a separate job—that only runs once—to combine and report coverage results after your test job has completed:

parallel = true

run = "python -m coverage run -m {module_tests}"

once = true
requires = ["test"]
run = [
    "python -m coverage combine",
    "python -m coverage report",

It is also common to desire seeing the coverage report, even when results are above minimum thresholds. In these cases, the coverage job can always show its output:

show_output = true

Continuous Integration

The current recommended way to use thx in CI jobs is by installing it from PyPI in the live environment:

$ pip install thx

thx should then be run with the --live flag to disable the version matrix, and only run jobs against the active runtime, rather than having a single CI job that tests all supported versions at once:

$ thx --live <job-name> ...

Github Actions

This build workflow will run separate jobs for each supported OS and Python version, and will install and run thx using the active Python version.

name: Build
      - main
      - v*

    runs-on: ${{ matrix.os }}
      fail-fast: false
        python-version: ["3.7", "3.8", "3.9", "3.10"]
        os: [macOS-latest, ubuntu-latest, windows-latest]

      - name: Checkout
        uses: actions/checkout@v3

      - name: Set Up Python ${{ matrix.python-version }}
        uses: actions/setup-python@v3
          python-version: ${{ matrix.python-version }}
          cache: 'pip'

      - name: Install thx
        run: pip install -U thx

      - name: Test
        run: thx --live test

      - name: Lint
        run: thx --live lint