Jest or Vitest setup for Express - Mini Project: Build & Apply

Jest Setup for Testing an Express Server

📖 Scenario: You are building a simple Express server and want to test its routes using Jest. Testing helps you catch errors early and ensures your server works as expected.

🎯 Goal: Set up Jest testing for an Express server by creating the server, configuring Jest, writing a test for a route, and completing the test setup.

📋 What You'll Learn

Create a basic Express server with one GET route

Add a Jest configuration variable

Write a Jest test to check the GET route response

Complete the test file with necessary imports and exports

💡 Why This Matters

🌍 Real World

Testing Express servers is essential in real projects to ensure routes work correctly and to prevent bugs before deployment.

💼 Career

Many backend developer roles require writing tests for APIs using Jest or Vitest to maintain code quality and reliability.

1

Create a basic Express server

Create a file app.js and write code to import express, create an app, and add a GET route at '/' that sends 'Hello World'. Export the app using module.exports = app.

Express

// Your code here

Need a hint?

Use express() to create the app and app.get to add a route.

2

Add Jest test configuration

Create a file jest.config.js and add a configuration object that sets testEnvironment to 'node'.

Express

// Your code here

Need a hint?

Jest needs testEnvironment: 'node' to test Express servers.

3

Write a Jest test for the GET route

Create a test file app.test.js. Import request from 'supertest' and import the app from './app'. Write a test using test that sends a GET request to '/' and expects the response text to be 'Hello World'.

Express

// Your code here

Need a hint?

Use supertest to send a GET request and check the response text.

4

Complete the test setup

Add module.exports = app at the end of app.js if missing, and ensure the test file imports app correctly. Confirm the test file includes the test function with the async callback and expect assertion.

Express

// Your code here

Need a hint?

Make sure the app is exported and the test imports it correctly to run the test.