404 handling middleware

In order to handle a 404 Not Found response, let's add a 404 not found middleware. Let's write a test, ./test/heartbeat.js; the content type returned should be JSON and the status code expected should be 404 Not Found:

describe('vision heartbeat api', function(){
  describe('when requesting resource /missing', function(){
    it('should respond with 404', function(done){
      request(app)
      .get('/missing')
      .expect('Content-Type', /json/)
      .expect(404, done);
    })
  });
});

Now, add the following middleware to ./lib/middleware/notFound.js. Here we export a function called index and call res.json, which returns a 404 status code and the message Not Found. The next parameter is not called as our 404 middleware ends the request by returning a response. Calling next would call the next middleware in our Express stack; we do not have any more middleware due to this, it's customary to add error middleware and 404 middleware as the last middleware in your server:

exports.index = function(req, res, next){
    res.json(404, 'Not Found.');
};

Now add the 404 not found middleware to ./lib/express/index.js:

var express = require('express')
  , http = require('http')
  , config = require('../configuration')
  , heartbeat = require('../routes/heartbeat')
  , notFound = require('../middleware/notFound')
  , app = express();

app.set('port', config.get('express:port'));
app.get('/heartbeat', heartbeat.index);
app.use(notFound.index);

http.createServer(app).listen(app.get('port'));
module.exports = app;