Passport, mocha, super exploitation ECONNREFUSED

I am trying to test authentication with mocha, supertest and passport, but I am getting a denied error. I guess it has to do with how I start my application ...

var testUser = {
    "email": "test@test.com",
    "password": "test"
};

var app = require('../../server');

var request = require('superagent');
var user = request.agent(app);

describe('authentication api ', function() {

    it('should login a user', function(done) {
        user.post('/login')
            .send(testUser)
            .end(function(err, res) {
                if(err) throw err;
                done();
            });
    });
});

      

        
        
        
      

    

This user exists in my mongo database. In my server file, which is two levels higher:

module.exports = app.listen(port, function() {
    console.log('app listening on port: ' + port);
});