End-to-End Testing with Supertest

1. Introduction

End-to-end (E2E) testing is crucial for ensuring that your web applications function correctly from the user's perspective. This lesson focuses on using Supertest, a powerful library for testing HTTP servers in Node.js applications.

2. What is Supertest?

Supertest is a testing library that allows you to test HTTP servers in Node.js. It provides a high-level abstraction for testing HTTP requests and responses, making it easy to validate the behavior of your APIs.

3. Setting Up

To get started with Supertest, you need to install it along with a testing framework like Mocha or Jest. Here’s how to set it up:

npm install supertest --save-dev

Ensure you have your Node application set up with the desired endpoints to test.

4. Writing Tests

Now let's write some tests using Supertest. Here’s a basic example of how you can test an Express.js API:

const request = require('supertest');
const app = require('./app'); // Your Express app

describe('GET /api/items', () => {
    it('should return a list of items', (done) => {
        request(app)
            .get('/api/items')
            .expect('Content-Type', /json/)
            .expect(200)
            .expect((res) => {
                if (!Array.isArray(res.body)) throw new Error('Response is not an array');
            })
            .end(done);
    });
});

5. Best Practices

• Keep tests isolated and independent.
• Use descriptive test names for clarity.
• Mock external APIs to avoid hitting them during tests.
• Run tests frequently to catch issues early.

6. FAQ