I see it referenced in several articles related to testing routes and MVC stuff in general.  Yet I cannot find it any assembly referenced by my project.  I have the latest MVC stuff referenced (Preview 4).

 Or more specifically, I have a UserService class that depends on HttpContext, how can I test this in a Unit Test project? I am using StructureMap for injection, and I am able to inject it using the HttpContextWrapper as a HttpContextBase, but I cannot get it to work in my Test project. 

This works in the web project, but not the Test project, obviously HttpContext.Current is null.

 ForRequestedType().TheDefaultIs(new HttpContextWrapper(HttpContext.Current));