Tests on the FluentAPI's use of the cache.

I really should write the tests when I write the code. Anyway, these test aim to verify that the Fluent Api:
- calls the TryGet method of the cache
- calls the Set method of the cache object on successful http
- does not call Set method of the cache object on a failure in http
- will return a value found in the cache 
-  will not call the http endpoint if a value is found in cache