Issues while exporting tests from StandAlone to VS Plug In

Unfortunately the Test Lists are deprecated in VS2012, but you can still use them.

Here's the workaround:

     1) Open your solution.
     2) From the Solution Explorer right click the solution item.
     3) Select Add/New Item
     4) Do not click on any of the available items, instead type in the text box 'TestList.vsmdi' or any other item name that ends with '.vsmdi'. Just make sure not to click on any item as it would overwrite your input.
     5) Find 'Solution Items' sub folder directly under your solution
     6) Double click TestList.vsmdi and this will bring up the 'Test List Editor' in VS2012.
     7) Select a test from the 'Test List Editor' and you'll find the Test Properties.
  
See this video for a demonstration.

Unfortunately in VS2012 you can only create a test list and edit it, but in order to execute the test list you need to use MSTest via the command line. You can read in this article more information how to use MSTest and how to execute a test list with a custom settings file.

Regards,