Quand je lance moka les tests que j'ai toujours d'Erreur: connexion ECONNREFUSED

Je suis en train de lancer mon application tests avec moka et supertest mais j'ai toujours l'Erreur: se connecter ECONNREFUSED.

app.js code:

var express = require('express'),
  mongoose = require('mongoose'),
  fs = require('fs'),
  config = require('./config/config');

mongoose.connect(config.db);
var db = mongoose.connection;
db.on('error', function () {
  throw new Error('unable to connect to database at ' + config.db);
});

var modelsPath = __dirname + '/app/models';
fs.readdirSync(modelsPath).forEach(function (file) {
  if (file.indexOf('.js') >= 0) {
    require(modelsPath + '/' + file);
  }
});

var app = express();

require('./config/express')(app, config);
require('./config/routes')(app);

app.listen(config.port);

exports.app = app;
console.log('LISTEN ON http://localhost:3000/')

test.js code:

var should = require('should'); 
var assert = require('assert');
var request = require('supertest');
var mongoose = require('mongoose');
var app = require('../../../app').app;

describe('Categories', function() {
    it('- POST is testing', function(done) {
        request(app)
        .post('http://localhost:3000/categories')
        .send({title:'test', text:'test'})
        .end(function(e, res) {
            console.log(e, res);
        });
    });
});

Test de sortie:

LISTEN ON http://localhost:3000/


  Categories
{ [Error: connect ECONNREFUSED]
  code: 'ECONNREFUSED',
  errno: 'ECONNREFUSED',
  syscall: 'connect' } undefined
    1) - POST is testing


  0 passing (2s)
  1 failing

Done, but with warnings.

Pourriez-vous nous donner aucune idée de pourquoi cela s'est vraiment passé?

Vous en remercie d'avance!

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