Stub doesn't return a value

I'm using Mocha as test runner, Chai for assertion and Sinon. I'm having trouble using sinon, I have the following function that I want to test in PrestigeQuoteService.js file

  find: function (criteria) {
    return PrestigeQuote.find(criteria)
      .populate('client')
      .populate('vehicle')
      .populate('quoteLogs');
  },

and here is my test case

  describe('find()', function () {
    describe('prestige quote found', function () {
      before(function () {
        sandbox = sinon.sandbox.create();
        var mockChain = {
          populate: function () {
            return this;
          }
        };
        sandbox
          .stub(PrestigeQuote, 'find').returns(mockChain);
      });

      it('should return a particular quote', function (done) {
        PrestigeQuoteService.find({id: 1}, function (err, result) {
          result.should.exist;
          done();
        });
      });

      after(function () {
        sandbox.restore();
      });
    });
  });

yet I get this error, even thought I have done() and should return value by default.

 Error: timeout of 10000ms exceeded. Ensure the done() callback is being called in this test.