We're now ready to get back to our original task – writing unit tests for our Create User request handler! You should have enough understanding to implement the unit tests for the handler yourself, but we'd like to first give you some hints with regards to promises.
If the function we are testing perform asynchronous operations, there's no guarantee that the asynchronous operations would complete before our assertion code is run. For instance, if our create engine function is actually very slow to resolve, like so:
function createUser() { aVerySlowCreate() .then((result) => { res.status(201); });}
Then the following test would fail:
describe("When create resolves with the new user's ID", function () { beforeEach(function ...
