Throw an Exception if TestClass attribute is specified along the STATestClass

[huserben]

Hi

I just encountered a problem by making the mistake of adding the STATestClass attribute along side of the "regular" TestClass.

So following situation:

 [STATestClass]
  [TestClass]
  public class UnitTest1
  {
     [TestMethod]
     public void TestMethod1()
     {
        var staTest = new MainWindow();
     }
  }

In the above case it's working fine. If we exchange the order and we have:

   [TestClass]
   [STATestClass]

It won't work anymore.
It would be good if the situation could be detected as in fact we only need one of the attributes. So ideally we would throw an exception with a meaningful error message so this problem is easily detected. So other people don't wonder why it's not working for them like for me.