How do I test async middleware in Express.js?

How do I test async middleware in Express.js?

To test async middleware in Express.js, you can use a testing framework like Mocha or Jest along with supertest.

Can you show me a code example?

Sure! Here's a simple example:

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

describe('Async Middleware', () => {
  it('should handle async middleware', async () => {
    const response = await request(app).get('/your-endpoint');
    expect(response.status).toBe(200);
  });
});

What if my middleware throws an error?

You can test error handling by simulating an error in your middleware and checking the response. For example:

app.use(async (req, res, next) => {
  throw new Error('Test error');
});

it('should handle errors', async () => {
  const response = await request(app).get('/your-endpoint');
  expect(response.status).toBe(500);
});