Sometimes, we want to test an Express app with Mocha.

In this article, we’ll look at how to test an Express app with Mocha.

How to test an Express app with Mocha?

To test an Express app with Mocha, we can make requests in our tests to the endpoint we’re testing with supertest.

For instance, we write

const request = require('supertest')
const {
  app
} = require('./express-app')
const assert = require("assert");

describe('POST /', () => {
  it('should fail', (done) => {
    request(app)
      .post('/')
      .send({
        'imgUri': 'foobar'
      })
      .expect(500)
      .end((err, res) => {
        done();
      })
  })
});

to call it with a callback with the test code.

In it, we call request with app to run the app.

And then we call post to make a POST request.

send sends the POST request body.

We then call expect to test the returned response code.

And then we call done in the end callback to finish the test.

Conclusion

To test an Express app with Mocha, we can make requests in our tests to the endpoint we’re testing with supertest.