You are aware that VS 2012 doesn't support test lists, right? That feature was deprecated starting with VS 2012. Microsoft wants you to use "Test Categories
" instead. We do realize that there is no way to put a Test Studio test into a test category at this time. This is high on our TODO list for the near future.
Even in VS 2010 (where you could have a test list) a Visual Studio test list and a Test Studio test list are very different and not interchangeable. Moving forward we are very unlikely to add the ability to run a Test Studio test list from Visual Studio, but we will probably add support for Test Categories so you can run groups of tests the way Microsoft wants you to using Visual Studio.