单元测试一个附加行为WPF

Question

我仍然所著的Grokking一般附加的行为，并且很茫然看如何写一个单元测试之一。

我粘贴从萨沙理发的束带框架下面一些代码，允许通过附加的行为被关闭的窗口。可以somewone告诉我一个例子的单元测试呢？

谢谢！点击 Berryl

    #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

Answer 1

您可能会使用ICommand或DelegateCommand使用lambda在RelayCommand。这些多重实现中存在所有的地方和束带可能有类似的东西。非常简单的版本（作为一个例子，并不是为生产使用）：

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
}

然后测试的身体可能是这个样子：

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 );

这是一个过于简单化的例子。还有的你要执行过程中其他的测试，在这种情况下，你应该创建或找到一个更全面执行DelegateCommand的也正常实施CanExecute，等等。

Answer 2

的DependencyProperty改变自己的样子对我来说“不可能依赖”和值胁迫。有参考窗口有使事情更加棘手。我想我会在这里谦逊的对象模式 ...

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