expressjsHow can I set up unit testing for an Express.js application?

Unit testing an Express.js application can be done using the popular testing framework Mocha. Mocha provides a simple way to set up tests for your application.

To get started, install Mocha using npm:

npm install --save-dev mocha

Then create a test directory in your application root, and create a test file (e.g. test/app.test.js) with the following content:

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

describe('GET /', () => {
  it('should return 200 OK', (done) => {
    request(app)
      .get('/')
      .expect(200, done);
  });
});

This test will ensure that a GET request to the root / route returns a 200 status code.

Finally, add a script to your package.json file to run the tests:

"scripts": {
  "test": "mocha"
}

Now you can run the tests from the command line with npm test:

npm test

This will print out the results of the tests.

Helpful links

• Mocha
• SuperTest

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