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Namah Shrestha
Namah Shrestha

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Chapter 6: Test on Commit With Github Actions

#github #testing #python #git

6.1 The Need for Github Actions

  • Everything we did with Tox is only local to our machine. That is, the tests pass in all the version, type check passes in all the versions and linting works in all the versions as well. However, all of it happens on our machine. That is, on our operating system.
  • How do we know that it passes on other machines? Other operating systems?
  • Well, this is the “AUTOMATED” part in Automated Testing.
  • Here we will configure Github Actions to automatically run Tox every time we make a push to the main branch across different machines (OS).

6.2 Configuring Github Actions

  • To configure Github Actions we need another configuration file. In this case, an entire directory.
  • We need to create the following files and directories: .github/workflows/<name>.yml.
  • In this case, name can be whatever we want. We will call it, tests.yml.

  • Let’s look at the tests.yml file.

    name: Tests

on:
  - push
  - pull_request

jobs:
  test:
    runs-on: ${{ matrix.os }}
    strategy:
      matrix:
        os: [ubuntu-latest, windows-latest]
        python-version: ['3.6', '3.7', '3.8', '3.9']

    steps:
    - uses: actions/checkout@v2
    - name: Set up Python ${{ matrix.python-version }}
      uses: actions/setup-python@v2
      with:
        python-version: ${{ matrix.python-version }}
    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install tox tox-gh-actions
    - name: Test with tox
      run: tox

  • We have the name field. This is the name that will show up on our badge in README.md.

  • We specify that we want to run our workflow to run on push or pull_request.

  • We only have one job. We call it test.

  • strategy->matrix is a syntax we use in order to create all combinations of environments that we want to use.

    • We have:

      os: [ubuntu-latest, windows-latest]
python-version: ['3.6', '3.7', '3.8', '3.9']

    • So there will be 8 virtual environments:

      • ubuntu-latest, 3.6
      • ubuntu-latest, 3.7
      • ubuntu-latest, 3.8
      • ubuntu-latest, 3.9
      • windows-latest, 3.6
      • windows-latest, 3.7
      • windows-latest, 3.8
      • windows-latest, 3.9

    • All of these values are preconfigured Github options. We cannot write custom names for these sections. We can find the link to all the supported options at the Github Actions documentation.

  • Now, we just define what are all the steps.

    • We checkout the repository.

      - uses: actions/checkout@v2
- name: Set up Python ${{ matrix.python-version }}

    • We setup the version of Python.

      uses: actions/setup-python@v2
  with:
    python-version: ${{ matrix.python-version }}

    • Install the dependencies.

      - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install tox tox-gh-actions

  • Run tox.

    - name: Test with tox
    run: tox

  • After the following steps. Whenever we commit and push to Github, we will see a build getting triggered. Github will automatically detect our workflow.

  • We can play around the Github UI from there.

  • Finally this is the project structure we have.

    - .github/
    - workflows/
        - tests.yml
- src/
    - something/
        - __init__.py
        - py.typed
        - app.py
- tests/
    - __init__.py
    - conftest.py
    - test_app.py
- .gitignore
- LICENSE
- pyproject.toml
- README.md
- requirements.txt
- setup.cfg
- setup.py
- tox.ini

6.3 Understanding Tox GH Actions

  • Notice in the tests.yml file that we install tox-gh-actions in the steps. We need to understand what this is.

    - name: Install dependencies
      run: |
        python -m pip install --upgrade pip
        pip install tox tox-gh-actions

  • Github already has its own set of actions that mimics what tox does.

  • We can use tox-gh-actions alone in our tox.ini file, if all we wanted to do was push to Github.

  • However, we are setting up tox with different blocks, because we want to run the tests locally and tox-gh-actions only runs on Github. We cannot run Github Actions locally.

  • tox-gh-actions is a tool to make tox and Github Actions work together.

  • We need to give Github a way to map our Tox environments with the github environments.

  • If we notice, we already have a gh-actions section on the tox.ini file.

    [gh-actions]
python =
    3.6: py36, mypy, flake8
    3.7: py37
    3.8: py38
    3.9: py39

  • The syntax is as follows:

    [gh-actions]
python =
    <github_python_version1>: <tox_env1>, <tox_env2>
        <github_python_version1>: <tox_env3>, <tox_env4>
        ...
    and so on

  • All we do is list out the name of the github environment and map it to the corresponding tox environments.

  • Again, our tox environment looks something like this:

    [tox]
minversion = 3.8.0
envlist = py36, py37, py38, py39, flake8, mypy
isolated_build = true

  • So we are basically mapping:
    - 3.6 to py36, flake8 and mypy. This is because if we look at the configuration of these environments in tox.ini. Their basepython field is only 3.6. Therefore, we did not map flake8 and mypy to the other versions.
    - 3.7 to py37.
    - 3.8 to py38.
    - 3.9 to py39.

6.3 Adding build results to README

  • We can add the results of the build in our [README.md](http://README.md) file.
  • We can do that by adding the following line on our README.md: ![Tests](https://github.com/<Username>/<ProjectName>/actions/workflows/tests.yml/badge.svg).

  • So our [README.md](http://README.md) file looks something like this.

    # Something
A starter project to show how to set up and use automated testing in Python

![Tests](https://github.com/DummyUser/DummyProject/actions/workflows/tests.yml/badge.svg)

  • So thats our article. Thank you for making it this far. To understand this article visually, checkout the video mentioned in the credits section.

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