I Used telerik:ListBox Control which has selection changed Event and for this event I was writing Unit Test code(X-Unit).
var selectionChangedEventArg = parameter as System.Windows.Controls.SelectionChangedEventArgs;
if (selectionChangedEventArg != null && selectionChangedEventArg.OriginalSource != null)
System.Windows.Controls.SelectionChangedEventArgs obj =
new System.Windows.Controls.SelectionChangedEventArgs(routedEvent, removedItems, addedItems);
selectionChangedEventArg.OriginalSource was null when the method is called from Test method. Any idea to make the original Source has value.