How do I test my Express.js application using Supertest?

How do I test my Express.js application using Supertest?

You can use Supertest to test your Express.js application by making HTTP requests to your endpoints. First, install Supertest using npm.

What is the basic setup for using Supertest?

To set up Supertest, you need to require it in your test file and create a request to your Express app. Here's a simple example:

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

describe('GET /api', () => {
  it('responds with json', async () => {
    const response = await request(app).get('/api');
    expect(response.status).toBe(200);
    expect(response.body).toEqual({ message: 'Hello World' });
  });
});

Can I test POST requests with Supertest?

Yes, you can test POST requests by using the .post() method. You can also send data in the request body. For example:

const response = await request(app)
  .post('/api/data')
  .send({ key: 'value' });
expect(response.status).toBe(201);

What about testing error responses?

You can test error responses by simulating invalid requests. For example, if you expect a 400 status for bad input, you can do:

const response = await request(app)
  .post('/api/data')
  .send({}); // sending empty data
expect(response.status).toBe(400);