GitHub Actions

Introduction

This articles introduces you to GitHub Actions and provides an example GitHub Action that runs unit tests on each GitHub commit push.

Github Actions

GitHub Actions is an additional product offering from GitHub Actions to aid developers in Continuous Integrations in their projects. It allows developers to build workflows (like running tests or building an image) on certain events (like pushing code to GitHub). GitHub uses runners to execute these tasks, which is a virtual machine (usually based on Linux, but can be customized to other OSes).

Each workflow consists of a series of steps called jobs. These steps may include building your code, running tests, or re-using existing actions available on the GitHub Marketplace.

Example

Let us take a look an example GitHub Action.

name: Run Jest Tests

on:
  push:
    branches:
      - master
  pull_request:
    branches:
      - master

jobs:
  test:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout repository
        uses: actions/checkout@v3

      - name: Set up Node.js
        uses: actions/setup-node@v3
        with:
          node-version: '20'

      - name: Install dependencies
        run: npm install

      - name: Run Jest tests
        run: npm test

1. The on part of the file tells GitHub Actions which events should trigger this workflow. In this case, it is commits on pushed to the master branch or when a pull request is merged to the master branch.

2. The jobs part of the file tells GitHub Actions what steps to execute. In this case, first Node.js v20 is setup on a Ubuntu Linux virtual machine. Then the dependencies are installed, and then the tests are run.

If you take a look at the Actions tab in a GitHub repository, you will be able to see the logs and status for each GitHub Action.

If you click any of the workflow runs, you will get a detailed list of steps executed.

In the above screenshot, we can see the run for “Add GitHub Action for tests #2” failed because some of the tests didn’t pass.

On fixing the code and pushing to the main branch, the “Add missing author field in createBook #3” workflow run passed and has a green checkmark.

This example is from: https://github.com/anikeshk/ci-books

You can find the GitHub action in the .github/workflows folder: https://github.com/anikeshk/ci-books/blob/master/.github/workflows/jest-test.yml

This is one example GitHub Action workflow. There are many more workflows that lint code, build images, perform static analysis of your code, and more! And they can be configured to run on each commit, when pushed to a certain branch, or manually. Check the References section for more examples.

GitHub Actions can be setup for any language supported by GitHub. Java and JavaScript/TypeScript are the popular options.

References

Official GitHub Documentation for GitHub Actions