Separate Express 'app' and 'server'

One Paragraph Explainer

The latest Express generator comes with a great practice that is worth to keep - the API declaration is separated from the network related configuration (port, protocol, etc). This allows testing the API in-process, without performing network calls, with all the benefits that it brings to the table: fast testing execution and getting coverage metrics of the code. It also allows deploying the same API under flexible and different network conditions. Bonus: better separation of concerns and cleaner code

Code example: API declaration, should reside in app.js

var app = express();
app.use(bodyParser.json());
app.use("/api/events", events.API);
app.use("/api/forms", forms);

Code example: Server network declaration, should reside in /bin/www

var app = require('../app');
var http = require('http');
/**
 * Get port from environment and store in Express.
 */
var port = normalizePort(process.env.PORT || '3000');
app.set('port', port);
/**
 * Create HTTP server.
 */
var server = http.createServer(app);

Example: test your API in-process using supertest (popular testing package)

const app = express();
app.get('/user', function (req, res) {
  res.status(200).json({ name: 'tobi' })
});
request(app)
  .get('/user')
  .expect('Content-Type', /json/)
  .expect('Content-Length', '15')
  .expect(200)
  .end(function (err, res) {
    if (err) throw err
  });