Was playing around with generics and suddenly my unit test project failed with this error: “Signature of the body and declaration in a method implementation do not match.” After some research I found a post here

http://social.msdn.microsoft.com/Forums/en-US/vststest/thread/b54e6634-1542-4bd8-a227-029bfb679dec

that explained my problem was using a private on a generic class, and was a known bug that won’t be fixed till VS 2010 as explained here

https://connect.microsoft.com/VisualStudio/feedback/ViewFeedback.aspx?FeedbackID=415357. 

Changed the private to public and was able to carry on.