public void TryGetTestExtensionShouldThrowExceptionWithNullUri()
 {
     testExtensionManager = new DummyTestExtensionManager(unfilteredTestExtensions, filteredTestExtensions, messageLogger);
     TestPluginCacheTests.SetupMockAdditionalPathExtensions();
     Assert.ThrowsException <ArgumentNullException>(() =>
     {
         var result = testExtensionManager.TryGetTestExtension(default(Uri));
     }
                                                    );
 }