Because it can be really helpful
The question that often comes up when talking to developers and clients about Web API solutions is how exactly should you go about testing your route configuration in Web API? Some would perhaps argue that in certain cases, especially if you stick to RESTful approach, this type of testing wouldn’t even be necessary, because the convention over configuration provided by the framework means that you effecitvely end up testing something that’s internal working of Web API.
With that said, especially when you have complex routes, or when you break the Restful approach and provide RPC-style API, or if you have your API actions decorated with HTTP verbs that don’t match the action names, you probably want to (and probably should, if you ask me) test the API routing to make sure certain requests end up in proper places.
Let’s deal with this interesting problem.