How to unit test Sails.js 0.10.8?

How can I test Sails.js with mocha.js?

Currently, my project structure is

project
--api
--assets
--tests
  |--services
     |--Utils.test.js
  |--bootstrap.test.js
  |--mocha.opts
....

Usually, I just write test cases in test/bootstrap.test.js and everything is fine. But test/services/Utils.test.js wouldn't tested and I don't know how to test Utils.test.js and bootstrap.test.js at once.

The code inside bootstrap.test.js is

var assert = require('assert');
var Sails = require('sails');

var sails;

describe("test sails", function ()
{
  before(function (done)
  {
    Sails.lift({}, function (err, server)
    {
      sails = server;
      if (err)
      {
        return done(err);
      }
      done(err, sails);
    });
  });

  describe("test Utils", function()
  {
    it('should equal 3', function (done)
    {
      assert.equal(Utils.add(1, 2),3);

      done();
    });
  });

  after(function (done)
  {
    var isDone = false;
    sails.lower(function()
    {
      if (!isDone)
      {
        done();
        isDone = true;
      }
    });
  });
});