I am sure many Developers/Testers might have asked this question to themselves. Perhaps it may also have been frustrating at times to see such a nifty feature just disappear.. But there is some good news - The Visual Studio Ranger team has an Add-In that got this capability back in 2012 & 2013.

You can get the tool from here - http://visualstudiogallery.msdn.microsoft.com/45208924-e7b0-45df-8cff-165b505a38d7

In fact, unlike the previous versions, Visual Studio now supports multiple Unit Tests Frameworks apart from just MSTEST. It's got built in support for nUnit & xUnit.

You can read up more from here - http://msdn.microsoft.com/en-us/library/hh704261(v=vs.110).aspx