public void RaiseCanExecuteChangedShouldRaiseEvent()
        {
            // arrange
            var command = new Mock<INotifyCommandChanged>();

            command.Setup( c => c.RaiseCanExecuteChanged() );

            var interceptor = new CommandInterceptor<object>( DefaultAction.None, DefaultAction.None, command.Object );

            // act
            interceptor.RaiseCanExecuteChanged();

            // assert
            command.Verify( c => c.RaiseCanExecuteChanged(), Times.Once() );
        }