When you design services around Http requests, you should really just inject your HttpClient as a dependency instead of wrapping it in a using statement in-place. This has the nice effect of making your code both easier to maintain and test. While doing a project recently, I decided to give Moq a try and use it to generate a HttpMessageHandler (that's the class the HttpClient uses internally for sending the network requests) for the HttpClient instead of providing my own HttpClient implementation. It's a really awesome mocking framework, but it took me a bit to set it up correctly. That's why I hope this snippet might save some of you a few minutes:

Happy mocking!