单元测试附加行为 wpf [英] unit test an attached behavior wpf

问题描述

我仍然在探索一般的附加行为，并且不知如何为一个行为编写单元测试.

I am still grokking attached behaviors in general, and am at a loss to see how to write a unit test for one.

我在下面粘贴了 Sacha Barber 的 Cinch 框架中的一些代码，该框架允许通过附加行为关闭窗口.有人可以给我看一个示例单元测试吗?

I pasted some code below from Sacha Barber's Cinch framework that allows a window to be closed via attached behavior. Can somewone show me an example unit test for it?

谢谢！
贝瑞尔

    #region Close

    /// <summary>Dependency property which holds the ICommand for the Close event</summary>
    public static readonly DependencyProperty CloseProperty =
        DependencyProperty.RegisterAttached("Close",
            typeof(ICommand), typeof(Lifetime),
                new UIPropertyMetadata(null, OnCloseEventInfoChanged));

    /// <summary>Attached Property getter to retrieve the CloseProperty ICommand</summary>
    public static ICommand GetClose(DependencyObject source)
    {
        return (ICommand)source.GetValue(CloseProperty);
    }

    /// <summary>Attached Property setter to change the CloseProperty ICommand</summary>
    public static void SetClose(DependencyObject source, ICommand command)
    {
        source.SetValue(CloseProperty, command);
    }

    /// <summary>This is the property changed handler for the Close property.</summary>
    private static void OnCloseEventInfoChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        var win = sender as Window;
        if (win == null) return;

        win.Closing -= OnWindowClosing;
        win.Closed -= OnWindowClosed;

        if (e.NewValue == null) return;

        win.Closing += OnWindowClosing;
        win.Closed += OnWindowClosed;
    }

    /// <summary>
    /// This method is invoked when the Window.Closing event is raised.  
    /// It checks with the ICommand.CanExecute handler
    /// and cancels the event if the handler returns false.
    /// </summary>
    private static void OnWindowClosing(object sender, CancelEventArgs e)
    {
        var dpo = (DependencyObject)sender;
        var ic = GetClose(dpo);
        if (ic == null) return;

        e.Cancel = !ic.CanExecute(GetCommandParameter(dpo));
    }

    /// <summary>
    /// This method is invoked when the Window.Closed event is raised.  
    /// It executes the ICommand.Execute handler.
    /// </summary>
    static void OnWindowClosed(object sender, EventArgs e)
    {
        var dpo = (DependencyObject)sender;
        var ic = GetClose(dpo);
        if (ic == null) return;

        ic.Execute(GetCommandParameter(dpo));
    }

    #endregion

推荐答案

您可能会使用 DelegateCommand 或 RelayCommand<在 ICommand 中使用 lambda/代码>.这些的多种实现无处不在，Cinch 可能有类似的东西.非常简单的版本(例如，不适合生产使用):

You would likely use a lambda in your ICommand using a DelegateCommand or a RelayCommand. Multiple implementations of these exists all over the place and Cinch may have something similar. Really simple version (as an example, not meant for production use):

public class DelegateCommand : ICommand {
    private Action _execute = null;

    public void Execute( object parameter ) {
        _execute();
    }

    public DelegateCommand( Action execute ) {
        _execute = execute;
    }

    #region stuff that doesn't affect functionality
    public bool CanExecute( object parameter ) {
        return true;
    }
    public event EventHandler CanExecuteChanged {
        add { }
        remove { }
    }
    #endregion
}

那么您的测试主体可能如下所示:

Then your test body might look something like this:

bool wascalled = false;

var execute = new DelegateCommand(
    () => {
        wascalled = true;
    } );

var window = new Window();
SomeClass.SetClose( window, execute );

// does the window need to be shown for Close() to work? Nope.

window.Close();

AssertIsTrue( wascalled );

这是一个过于简化的例子.当然，您还需要执行其他测试，在这种情况下，您应该创建或找到更完整的 DelegateCommand 实现，该实现也正确实现了 CanExecute 等.

This is an over-simplified example. There are of course other tests you'll want to perform, in which case you should create or find a fuller implementation of DelegateCommand that also properly implements CanExecute, among other things.

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