Writing CI Workflows: Lint and Test

Writing CI Workflows: Lint and Test

The most common use of GitHub Actions is Continuous Integration (CI) — automatically running tests and code quality checks on every push and pull request. This ensures that broken code never reaches the main branch.

A Node.js CI Workflow

name: Node.js CI

on:
push:
branches: [ main ]
pull_request:
branches: [ main ]

jobs:
test:
runs-on: ubuntu-latest

steps:
- name: Checkout code
uses: actions/checkout@v4

- name: Set up Node.js
uses: actions/setup-node@v4
with:
node-version: '20'
cache: 'npm'

- name: Install dependencies
run: npm ci

- name: Run linter
run: npm run lint

- name: Run tests
run: npm test

Key Actions Explained

actions/checkout@v4 clones your repository into the runner. actions/setup-node@v4 installs Node.js. The cache: 'npm' option caches the npm dependency cache between runs, dramatically speeding up subsequent workflow executions.

Matrix Strategy

Run tests on multiple Node.js versions simultaneously:

strategy:
matrix:
node-version: [18, 20, 22]

steps:
- uses: actions/setup-node@v4
with:
node-version: ${{ matrix.node-version }}

This creates three parallel jobs, one for each Node.js version.