As you are creating a mockup of a asynchronous method, you need to add `setTimeout` in order to emulate the real behaviour. This is the big change here, because when updating this all tests are going to fail. However, as you have done in some of the tests, you can use `done` param for testing the async. methods! So for example https://github.com/borjasalguero/gaia/pull/35/files#diff-47d5dbb32aa2666155b03820c8820affR62 could be called within the callback of `onNext`.