Automation Event Handlers are fired more than once

Question

I'm working with the MS UIA framework and its built-in Automation event handling. I'm seeing unexpected behavior on the WindowClosedEvent.

Perhaps I'm doing something wrong here, but my understanding was that the Console call should be executed once. When I run the above code the Console line is executed twice.

When my TestApp is close there are no special events that it runs. The test app is also only a single WPF window.

[TestMethod]
    public void TestMethod1()
    {
        Process.Start(@"TestApp.exe");

        Thread.Sleep(2000); //sleep to wait for proc to boot with ui

        var windowElement = AutomationElement.RootElement.FindFirst(TreeScope.Descendants,
            new AndCondition(new PropertyCondition(AutomationElement.ControlTypeProperty, ControlType.Window),
                new PropertyCondition(AutomationElement.NameProperty, "TestApp"), new PropertyCondition(AutomationElement.AutomationIdProperty, "TestAppAutomationId")));



        Automation.AddAutomationEventHandler(WindowPattern.WindowClosedEvent, windowElement, TreeScope.Element,
            OnClose);

        var windowPattern = (WindowPattern)windowElement.GetCurrentPattern(WindowPattern.Pattern);

        windowPattern.Close();


        Thread.Sleep(2000); //sleep to wait for uia's event threads to fire and finish.
    }

    public void OnClose(object sender, AutomationEventArgs e)
    {
        Console.WriteLine("test");  //this is run twice during the test
    }

I'm running against .NET 4.5.2 on Windows 10.

If I'm doing something wrong here that would cause the handler to fire more than once please let me know.

Thanks.

Answer 1

The solution problem is we found that in return to event call it return a value

   ( AutomationPropertyChangedEventArgs e)

the above event have property value that is passed to function so

           private void Property_Change_Event(object src, AutomationPropertyChangedEventArgs e)
    {
        AutomationElement sourceElement = src as AutomationElement;
        if (   e.Property  ==   WindowPatternIdentifiers.WindowClosedEvent)
        {
              //manage e.NewValue == 0 or  1

        }