I have some tests that use the built in Microsoft.VisualStudio.TestTools.UnitTesting, but can not get them to run.
I am using visual studio 2012 ultimat
Check referenced assemblies for any assemblies that may have "Copy Local" set to "False".
If your test project builds to it's own folder (bin/Debug for example) and the project depends on another assembly and one of those assemblies in the References list is marked Copy Local = "False", the assembly cannot load due to missing dependencies and your tests will not load after a build.