title: Unit Tests in Visual Studio 2015 don't run
body: <p>Neither the integrated test environment nor Resharper won't run any unit tests.</p>
  
  <p>When starting Visual Studio the Test Output Pane shows 10+ lines stating:</p>
  
  <blockquote>
    <p>An exception was thrown while initializing part "Microsoft.VisualStudio.TestWindow.Controller.TestPlatformProvider".</p>
  </blockquote>
  
  <p>This is what I've tried so far:</p>
  
  <ul>
  <li>Clear folder %LocalAppData%\Microsoft\VisualStudio\14.0\ComponentModelCache</li>
  <li>Create a simple test project with one class library, one class and one test library containing one unit test for that class</li>
  <li>Uninstallation and new installation of Visual Studio 2015</li>
  </ul>
  
  <p>All actions didn't fix the problem. Even the simple test won't run.</p>
  
  <p>Running tests from command line using MSTest does work.</p>