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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 .github/workflows

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

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name: Run Tests

on:
  push:
    branches: [dev]

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

    steps:
    - uses: actions/checkout@v4
    - name: Install poetry
      run: pipx install poetry
    - uses: actions/setup-python@v5
      with:
        python-version: '3.10'
        cache: 'poetry'
    - run: poetry install
    - name: Run pre-commit checks
      run: |
        poetry run pre-commit run --all-files

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

    steps:
    - uses: actions/checkout@v4
    - name: Install poetry
      run: pipx install poetry
    - uses: actions/setup-python@v5
      with:
        python-version: '3.10'
        cache: 'poetry'
    - run: poetry install
    - name: Run tests
      run: |
        poetry 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: [dev]

We give the workflow a name Run Tests. Then we say, whenever a push is made to dev, 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
    - name: Install poetry
        run: pipx install poetry
    - uses: actions/setup-python@v5
        with:
        python-version: '3.10'
        cache: 'poetry'
    - run: poetry install
    - name: Run pre-commit checks
        run: |
        poetry 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 poetry with python version 3.10
  2. Install the package with poetry install
  3. Run the pre-commit on our files.

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

The test cases

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

steps:
- uses: actions/checkout@v4
- name: Install poetry
    run: pipx install poetry
- uses: actions/setup-python@v5
    with:
    python-version: '3.10'
    cache: 'poetry'
- run: poetry install
- name: Run tests
    run: |
    poetry 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 poetry 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.

Further reading