问题
When I open Visual Studio 2013 and load my solution I'm greeted by an error message telling me the Test Window is unable to load.
The composition produced a single composition error. The root cause is provided below. Review the CompositionException.Errors property for more detailed information.
1) Cannot compose part 'Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal' because a cycle exists in the dependencies between the exports being composed. To break this cycle, consider changing some imports from constructor to property injection.
Element: Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal --> Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal
Resulting in: Cannot get export 'Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal (ContractName="Microsoft.VisualStudio.TestWindow.Data.TestsService+ITestsServiceInternal")' from part 'Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal'.
Element: Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal (ContractName="Microsoft.VisualStudio.TestWindow.Data.TestsService+ITestsServiceInternal") --> Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal
The composition produced a single composition error. The root cause is provided below. Review the CompositionException.Errors property for more detailed information.
1) An operation is not legal in the current state. (Exception from HRESULT: 0x80131509)
Resulting in: An exception occurred while trying to create an instance of type 'Microsoft.VisualStudio.TestWindow.VsHost.TestWindowHost'.
Resulting in: Cannot activate part 'Microsoft.VisualStudio.TestWindow.VsHost.TestWindowHost'.
Element: Microsoft.VisualStudio.TestWindow.VsHost.TestWindowHost --> Microsoft.VisualStudio.TestWindow.VsHost.TestWindowHost
Resulting in: Cannot get export 'Microsoft.VisualStudio.TestWindow.VsHost.TestWindowHost (ContractName="Microsoft.VisualStudio.TestWindow.Controller.IOpenResult")' from part 'Microsoft.VisualStudio.TestWindow.VsHost.TestWindowHost'.
Element: Microsoft.VisualStudio.TestWindow.VsHost.TestWindowHost (ContractName="Microsoft.VisualStudio.TestWindow.Controller.IOpenResult") --> Microsoft.VisualStudio.TestWindow.VsHost.TestWindowHost
Resulting in: Cannot set import 'Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal..ctor (Parameter="openResult", ContractName="Microsoft.VisualStudio.TestWindow.Controller.IOpenResult")' on part 'Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal'.
Element: Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal..ctor (Parameter="openResult", ContractName="Microsoft.VisualStudio.TestWindow.Controller.IOpenResult") --> Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal
Resulting in: Cannot get export 'Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal (ContractName="Microsoft.VisualStudio.TestWindow.Data.TestsService+ITestsServiceInternal")' from part 'Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal'.
Element: Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal (ContractName="Microsoft.VisualStudio.TestWindow.Data.TestsService+ITestsServiceInternal") --> Microsoft.VisualStudio.TestWindow.Controller.TestsServiceInternal
Visual Studio is unable to run tests at all. Closing an re-opening the test window shows the same error.
回答1:
This seems to be caused by a corruption in the Component Model Cache.
Close all instances of Visual Studio, then navigate to folder and delete it.
%LOCALAPPDATA%\Microsoft\VisualStudio\12.0\ComponentModelCache
Now restart Visual Studio and it should work again.
回答2:
Deleting solution.v12.suo and solution.suo can help resolve the problem as well.
回答3:
Just close and re-open Visual Studio (2015) may help.
回答4:
I tried to best answer (navigate to folder and delete it. %LOCALAPPDATA%\Microsoft\VisualStudio\12.0\ComponentModelCache) and it didn't work BUT, based on this method I found the solution which works for me :
navigate to folder and delete it : %LOCALAPPDATA%\Microsoft\WDExpress\11.0\ComponentModelCache
Hope I can help some people this way
来源：https://stackoverflow.com/questions/20301697/visual-studio-2013-is-unable-to-open-the-test-window