Skip to main content

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);
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;
  });