Having constructed the request in the last episode, our plucky team now focuses on mocking out the Smarty Streets API. They build a FakeHTTPClient that accepts the request and produces a valid, if canned, JSON response.

Watch carefully has these two extremely experienced programmers focus on the periphery of the problem, rather than "going for the gold." They make sure all the mechanics work properly, and all the error handing is managed. They are methodical, they are diligent, and they are very professional.