PyTest With GitHub Actions

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This is Day 20 of the #100DaysOfPython challenge.

This post will build off previous work done in the Python Unit Testing With PyTest post to add a GitHub Action for running test runner jobs on a push event to the repo.

The final project code can be found on my GitHub repo.

Prerequisites

Familiarity with Pipenv. See here for my post on Pipenv.
Read Python Unit Testing With PyTest if you are unfamiliar with Python.

Getting started

Let's clone the original PyTest repo in hello-pytest-github-actions.

$ git clone https://github.com/okeeffed/hello-pytest.git hello-pytest-github-actions
$ cd hello-pytest-github-actions

# Install the deps
$ pipenv install

# Prepare the file for the GitHub action
$ mkdir -p .github/workflows
$ touch .github/workflows/pytest.yml

At this stage, we can test that our repo is working correctly with PyTest locally:

$ pipenv run pytest
============================== test session starts ==============================
platform darwin -- Python 3.9.6, pytest-6.2.4, py-1.10.0, pluggy-0.13.1
rootdir: /path/to/code/blog-projects/hello-pytest
collected 3 items

tests/test_math.py ...                                                    [100%]

=============================== 3 passed in 0.01s ===============================

At this stage, we are ready to set things up for our GitHub action!

Adding the test script

In of the Pipfile, we want to add a [scripts] section to add a test script:

[[source]]
url = "https://pypi.org/simple"
verify_ssl = true
name = "pypi"

[packages]

[dev-packages]
pytest = "*"

[requires]
python_version = "3.9"

[scripts]
test = "pytest"

That test script will simply call pytest. We will use this script within our GitHub action.

In order to also prepare our GitHub action to give us more vebose information, we will also be passing a -v flag to our call to pytest.

We can test things are working as expected by running pipenv run test -v from our terminal:

$ pipenv run test -v
========================== test session starts ===========================
platform darwin -- Python 3.9.6, pytest-6.2.4, py-1.10.0, pluggy-0.13.1 -- /Users/dennisokeeffe/code/blog-projects/hello-pytest/.venv/bin/python
cachedir: .pytest_cache
rootdir: /Users/dennisokeeffe/code/blog-projects/hello-pytest-github-actions
collected 3 items

tests/test_math.py::test_add PASSED                                [ 33%]
tests/test_math.py::test_subtract PASSED                           [ 66%]
tests/test_math.py::test_multiply PASSED                           [100%]

=========================== 3 passed in 0.02s ============================

The verbose flag gives us more information about which test ran and passed. This can be helpful for debugging in CI.

Adding the GitHub action

We are now ready to add the GitHub action. Within the .github/workflows/pytest.yml file that we created earlier, add the following:

# .github/workflows/app.yaml
name: PyTest
on: push

jobs:
  test:
    runs-on: ubuntu-latest
    timeout-minutes: 10

    steps:
      - name: Check out repository code
        uses: actions/checkout@v2

      # Setup Python (faster than using Python container)
      - name: Setup Python
        uses: actions/setup-python@v2
        with:
          python-version: "3.x"

      - name: Install pipenv
        run: |
          python -m pip install --upgrade pipenv wheel
      - id: cache-pipenv
        uses: actions/cache@v1
        with:
          path: ~/.local/share/virtualenvs
          key: ${{ runner.os }}-pipenv-${{ hashFiles('**/Pipfile.lock') }}

      - name: Install dependencies
        if: steps.cache-pipenv.outputs.cache-hit != 'true'
        run: |
          pipenv install --deploy --dev
      - name: Run test suite
        run: |
          pipenv run test -v

Here we are doing a couple of things:

Creating a job call PyTest.
Running this job on a push event to the repository.
Running the job on ubuntu-latest.
Setting a custom timeout of 10 minutes (albeit this is overkill, feel free to omit).
Setting up the Python environment for the latest in version 3.x.
Install pipenv and wheel.
Install dependencies with a cache set to be the hash of the lockfile.
Running the test suite that we setup the command and tested before.

That is all that we need for this repo to be working!

Be sure at this stage that you have set up your own origin remote for the repo.

At this stage, all we need to do is commit the code and push the repo and the job will be available under the actions tab in the GitHub UI.

Summary

Today's post demonstrated how to use GitHub actions to test Python code on a push to the remote repository. We used the pytest testing framework to test our code.