Using Travis CI with Express.js

Introduction

Continuous Integration (CI) is the practice of automating the integration of code changes from multiple contributors into a single software project. Travis CI is a popular, hosted CI service used to build and test software projects hosted on GitHub.

Whenever you push code to GitHub, Travis CI can automatically run your unit tests, ensuring you never deploy broken code.

Configuration

To use Travis CI, you must add a .travis.yml file to the root of your Express project. This file tells Travis what programming language you are using, what versions to test against, and what scripts to run.

language: node_js
node_js:
  - "18"
  - "20"
  - "node" # This points to the latest stable version

# Services required for testing (e.g., if your tests need a database)
services:
  - mongodb
  - redis-server

# The script to run tests
script:
  - npm run lint
  - npm test

Setting up Travis

1. Go to travis-ci.com and sign in with your GitHub account.
2. Accept the authorization of Travis CI.
3. Sync your GitHub repositories.
4. Flick the switch next to your Express repository to enable Travis.
5. Push a commit to GitHub!

Travis will now spin up an isolated virtual machine, install your package.json dependencies, and run your script commands. If any command exits with a non-zero exit code (like a failed test), the build will fail, and GitHub will block you from merging the Pull Request.

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