public void ExecuteCancelCommandShouldExecuteExpectedCommand()
        {
            // arrange
            var command = new Mock<INamedCommand>();

            command.Setup( c => c.CanExecute( It.IsAny<object>() ) ).Returns( true );
            command.Setup( c => c.Execute( It.IsAny<object>() ) );

            var interaction = new Interaction()
            {
                CancelCommandIndex = 0,
                Commands = { command.Object }
            };

            // act
            interaction.ExecuteCancelCommand();

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