For me, it seems it was the project. I simply added a new test project to my solution "Unit Test Project (.Net Framework)" and moved all my test (cs) files to that project. All is working now. I had taken the advice of executing my test project within a command window (as suggested above) and the result mentioned that MsTest was legacy. That is what prompted me to just add a new project and move my code files to it. All works now.