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Testing

The process of automated testing is a little more involved, and we now introduce GitHub Actions.

The testing workflow

Create a new directory 

mkdir -p .github/workflows # (1)!

  1. The -p flag creates the entire directory structure if it does not exist.

and add a file in this directory called tests.yml. Now add the following

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name: Run Tests

on:
  push:
    branches-ignore:
      - main

jobs:
  pre-commit:
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v4
    - uses: actions/setup-python@v5
      with:
        python-version: '3.12'
        cache: 'pip'
    - name: Install uv
      run: curl -LsSf https://astral.sh/uv/install.sh | sh
    - name: Sync environment
      run: uv sync
    - name: Run pre-commit checks
      run: uv run pre-commit run --all-files

  tests:
    needs: pre-commit
    runs-on: ubuntu-latest

    steps:
    - uses: actions/checkout@v4
    - uses: actions/setup-python@v5
      with:
        python-version: '3.12'
        cache: 'pip'
    - name: Install uv
      run: curl -LsSf https://astral.sh/uv/install.sh | sh
    - name: Sync environment
      run: uv sync
    - name: Run tests
      run: uv run python -m unittest discover tests/

Let's walk through what we have done here.

Choose when the workflow runs

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name: Run Tests

on:
  push:
    branches-ignore:
      - main

We give the workflow a name Run Tests. Then we say, whenever a push is made to any branch other than main, run this workflow.

The jobs

Next, we define what jobs we want to run. In this case we have two: the pre-commit, and the tests.

The pre-commit checks

pre-commit:
  runs-on: ubuntu-latest

  steps:
  - uses: actions/checkout@v4
  - uses: actions/setup-python@v5
    with:
      python-version: '3.12'
      cache: 'pip'
  - name: Install uv
    run: curl -LsSf https://astral.sh/uv/install.sh | sh
  - name: Sync environment
    run: uv sync
  - name: Run pre-commit checks
    run: uv run pre-commit run --all-files

We choose what OS we want to run on, in this case the latest version of Ubuntu. Then we define what steps to take:

  1. Install python 3.12.
  2. Install uv
  3. Sync the project dependencies (uv sync)
  4. Run the pre-commit on our files.

So this entire thing is the equivalent to us saying uv run pre-commit run --all-files from before.

The test cases

tests:
  needs: pre-commit
  runs-on: ubuntu-latest

  steps:
  - uses: actions/checkout@v4
  - uses: actions/setup-python@v5
    with:
      python-version: '3.12'
      cache: 'pip'
  - name: Install uv
    run: curl -LsSf https://astral.sh/uv/install.sh | sh
  - name: Sync environment
    run: uv sync
  - name: Run tests
    run: uv run python -m unittest discover tests/

We have defined an extra field here needs: pre-commit. This ensures that this part of the workflow will not run unless the pre-commit checks all pass. If there are problems with our code, what's the point of running the tests? Fix the issues first, then resubmit.

We then install uv and python again, and run the unittests. So now, everytime we push changes to the dev branch, we will initilize this workflow!

Tip

It is also possible to use multiple versions of python and even different operating systems using the matrix strategy:

jobs:
    example_matrix:
        strategy:
            matrix:
            os: [ubuntu-latest, macos-latest]
            version: [3.10, 3.11, 3.12]
        runs-on: ${{ matrix.os }}
        steps:
            - uses: actions/setup-python@v5
            with:
                python-version: ${{ matrix.version }}

The world of GitHub Actions workflows is complex and full of danger. My advice is to keep it simple.


Dark Souls Bonfire

Now that we have our tests set up, let's try pushing these changes to our remote. You can head over to the Actions tab on your GitHub repository to see the workflow in action.

GitHub Actions

Further reading