VS 2010 Test Runner error “The agent process was stopped while the test was running.”

Question

In Visual Studio 2010, I have a number of unit tests. When I run multiple tests at one time using test lists, I sometimes reveive the following error for one or more of the

Answer 1

I was able to find the source of my problem by looking in the test result file (/TestResults/*.trx) It provided the full details of the exception that occurred in the background thread, and once I resolved that exception the "agent processed stopped..." error went away.

In my case I was unintentionally launching the GUI in my unit test, which eventually caused a System.ComponentModel.InvalidAsynchronousStateException to be thrown.

So my .trx file contained:

   
    One of the background threads threw exception: 
System.ComponentModel.InvalidAsynchronousStateException: An error occurred invoking the method.  The destination thread no longer exists.
at System.Windows.Forms.Control.WaitForWaitHandle(WaitHandle waitHandle)
at System.Windows.Forms.Control.MarshaledInvoke(Control caller, Delegate method, Object[] args, Boolean synchronous)
at System.Windows.Forms.Control.Invoke(Delegate method, Object[] args)
at System.Windows.Forms.Control.Invoke(Delegate method)
...

  

This didn't provide any information on what test caused the error, but it did show me where the exception was, which was very useful.