🛠️ What is GitHub Actions?

GitHub Actions is a feature of GitHub that lets you create automated workflows for your software projects—right inside your GitHub repository.

📌 What can you do with GitHub Actions?

You can build CI/CD pipelines (Continuous Integration / Continuous Deployment), such as:

• ✅ Automatically test code (e.g. with PHPUnit, Jest, Pytest)

• 🛠️ Build your app on every push or pull request

• 🚀 Automatically deploy (e.g. to a server, cloud platform, or DockerHub)

• 📦 Create releases (e.g. zip packages or version tags)

• 🔄 Run scheduled tasks (cronjobs)

🧱 How does it work?

GitHub Actions uses workflows, defined in a YAML file inside your repository:

• Typically stored as .github/workflows/ci.yml

• You define events (like push, pull_request) and jobs (like build, test)

• Each job consists of steps, which are shell commands or prebuilt actions

Example: Simple CI Workflow for Node.js

name: CI

on: [push]

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - uses: actions/setup-node@v3
        with:
          node-version: '20'
      - run: npm install
      - run: npm test

🧩 What are "Actions"?

An Action is a single reusable step in a workflow. You can use:

• Prebuilt actions (e.g. actions/checkout, setup-node, upload-artifact)

• Custom actions (e.g. shell scripts or Docker-based logic)

You can explore reusable actions in the GitHub Marketplace.

💡 Why use GitHub Actions?

• Saves time by automating repetitive tasks

• Improves code quality through automated testing

• Enables consistent, repeatable deployments

• Integrated directly in GitHub—no need for external CI tools like Jenkins or Travis CI

Jest is a JavaScript testing framework developed by Meta (Facebook). It is mainly used for testing JavaScript and TypeScript applications, especially React applications, but it also works well for Node.js backends.

Key Features of Jest:

• Easy Configuration: Jest works "out of the box" with minimal setup.
• Speed: It uses parallelization and intelligent caching for fast test execution.
• Snapshot Testing: Ideal for UI tests to ensure the output remains consistent.
• Mocking & Spying: Allows replacing dependencies with mock functions.
• Code Coverage Reports: Shows how much of the code is covered by tests.

Example of a Simple Jest Test:

// sum.js
function sum(a, b) {
  return a + b;
}
module.exports = sum;

// sum.test.js
const sum = require('./sum');

test('addiert 1 + 2 und ergibt 3', () => {
  expect(sum(1, 2)).toBe(3);
});

o run the test, use:

jest

Or, if installed locally in a project:

npx jest