Visual Studio Test Explorer window will not open

Window -> Reset Window Layout fixed the problem for me.

For me the fix was:

• Focus on the test window by Test > Windows > TestExplorer

• Using Win+Left / Right to move the window onto an active screen

  >    ┌┬┐
  > Win├┼┤ + Left or Right key
  >    └┴┘
  

The same worked for the ReSharper Unit Test Sessions window.

Found this solution here, which is the only thing that worked for me.

Delete all files from this folder: user\AppData\Local\Microsoft\VisualStudio\11.0\ComponentModelCache

In VS2012, Test Explorer has a bug in that the window doesn't get focus when you click Test > Windows > Test Explorer. Instead, the menu item has no effect unless the window was complete hidden, in which case it is displayed.

The bug means that if Test Explorer is collapsed with Auto Hide, the menu item does nothing. Check that Test Explorer isn't in an auto-hide tab somewhere off to the left or right (i.e. in a tab with text written vertically, like Server Explorer and Toolbox are by default).

Update: The bug is fixed in VS2013.