Memo

http://msdn.microsoft.com/en-us/library/hh549176.aspx

Shim types are one of two technologies that the Microsoft Fakes Framework uses to let you easily isolate components under test from the envirement. Shims divert calls to specific methods to code that you write as part of your test. Many methods return different results dependent on external conditions, but a shim is under control of your test and can return consistent results at every call. This makes your tests much easier to write.

http://msdn.microsoft.com/en-us/library/aa292114(v=vs.71).aspx

http://msdn.microsoft.com/en-us/library/system.web.httprequest.unvalidated.aspx