ContentControl is not visible when application starts via UI Automation test, but its visible when application starts by user

Question

We are using the prism and WPF to build application. Recently we started using UI Automation (UIA) to test our app. But some strange behavior occurred when we run UIA test. Here's simplified shell:

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*"/>
    </Grid.ColumnDefinitions>    
    <Grid.RowDefinitions>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>

    <TextBlock 
        Grid.Row="0" Grid.Column="0"
        Name="loadingProgressText"
        VerticalAlignment="Center" HorizontalAlignment="Center"
        Text="Loading, please wait..."/>

    <Border
        Grid.Row="0" 
        x:Name="MainViewArea">
        <Grid>
            ...
        </Grid>
    </Border>

    <!-- Popup -->
    <ContentControl 
        x:Name="PopupContentControl"
        Grid.Row="0" 
        prism:RegionManager.RegionName="PopupRegion"
        Focusable="False">
    </ContentControl>

    <!-- ErrorPopup -->
    <ContentControl 
        x:Name="ErrorContentControl"
        Grid.Row="0" 
        prism:RegionManager.RegionName="ErrorRegion"
        Focusable="False">
    </ContentControl>
</Grid>

In our app, we use layers (Popup and ErrorPopup) to hide MainViewArea, to deny access to the controls. To show Popup, we use next method:

    //In constructor of current ViewModel we store _popupRegion instance to the local variable:
    _popupRegion = _regionManager.Regions["PopupRegion"];
    //---

    private readonly Stack<UserControl> _popups = new Stack<UserControl>();
    public void ShowPopup(UserControl popup)
    {
        _popups.Push(popup);

        _popupRegion.Add(PopupView);
        _popupRegion.Activate(PopupView);
    }

    public UserControl PopupView
    {
        get
        {
            if (_popups.Any())
                return _popups.Peek();
            return null;
        }
    }

Similar to this, we show ErrorPopup over all elements of our application:

    // In constructor we store _errorRegion:
    _errorRegion = _regionManager.Regions["ErrorRegion"]
    // --- 

    private UserControl _error_popup;

    public void ShowError(UserControl popup)
    {
        if (_error_popup == null)
        {
            _error_popup = popup;
            _errorRegion.Add(_error_popup);
            _errorRegion.Activate(_error_popup);
        }
    }

Mistics...

When we run it as users do it (double click on app icon), we can see both custom controls (using AutomationElement.FindFirst method, or through Visual UI Automation Verify). But when we start it using UI Automation test - ErrorPopup disapears from the tree of the controls. We trying to start the application like this:

System.Diagnostics.Process.Start(pathToExeFile);

I think that we missed something. But what?

Edit #1

As @chrismead said, we tried to run our app with UseShellExecute flag set to true, but this does not help. But if we start app from cmd line, and manually click the button, Popup and ErrorPopup are visible in automation controls tree.

    Thread appThread = new Thread(delegate()
        {
            _userAppProcess = new Process();
            _userAppProcess.StartInfo.FileName = pathToExeFile;
            _userAppProcess.StartInfo.WorkingDirectory = System.IO.Directory.GetCurrentDirectory();
            _userAppProcess.StartInfo.UseShellExecute = true;
            _userAppProcess.Start();

        });
        appThread.SetApartmentState(ApartmentState.STA);
        appThread.Start();

One of our suggestion is when we use method FindAll or FindFirst to search the button to click, window somehow cached its UI Automation state, and does not update it.

Edit #2 We have find, that extension method of prism library IRegionManager.RegisterViewWithRegion(RegionNames.OurRegion, typeof(Views.OurView)) have some strange behavior. If we stopped use it, this solve our problem particulary. Now we able to see ErrorView and any kind of view in PopupContentControl, and application updates UIA elements tree structure. But this is not an answer - "Just stop use this feature"!

In MainViewArea we have a ContentControl, which updates it content depending on user actions, and we are able to see only the first loaded UserControl to that ContentControl.Content property. This is performed like this:

IRegionManager regionManager = Container.Resolve<IRegionManager>();
regionManager.RequestNavigate(RegionNames.MainContentRegion, this.Uri);

And if we change the view, no updates will performed in UI Automation tree - the first loaded view will be in it instead. But visually we observe another View, and WPFInspector shows it properly (its show not a UI Automation tree), but Inspect.exe - not.

Also our suggestion that window use some kind of caching is wrong - caching in UI Automation client we have to turn on explicitly, but we don't do it.

So, is it correct to say that a simple double click launch of the app results in the control being in the tree, but a Process.Start launch does not? — chrismead, Jun 13 '12 at 14:46
Yes, its correct. But we tried 3 way to start app from the code - no one is get us to the right solution... — stukselbax, Jun 13 '12 at 15:02
Have you tried launching the app from a cmd window? If that works then using the ProcessStartInfo.UseShellExecute flag might work. — chrismead, Jun 13 '12 at 15:04
Might not be related, but in Silverlight (so not quite WPF) our `ContentControl` isn't initialized/rendered until actually viewed on the screen; specifically, it's `Loaded` event is not fired. If the browser window was minimized, or behind other windows, it never fires the `Loaded` event. However, once the user restores the window or reorganizes their content so the Silverlight runtime renders the screen, then the `Loaded` event fires automatically. So yeah, not sure if this is relevant, or even how to get around this for an automated test. — Chris Sinclair, Jun 20 '12 at 18:20

stukselbax · Accepted Answer · 2012-06-26T04:19:14.863

I'm sorry that I've missed some detail, that was the key to the answer. I think that it was not important thing. Anyway.

We used NavBar from DevExpress controls library for WPF. What turns out, is when NavBar is present, dynamically created views are not appears on the UI Automation tree. When remove it from the window, there was an ability to see all dynamically loaded views. What does the NavBar - still mistic for me.

Here bright example to see what happened, if NavBar is present or absent on the Window (DevExpress is required).

MainWindow.xaml:

<Window xmlns:dxn="http://schemas.devexpress.com/winfx/2008/xaml/navbar"
        x:Class="Test.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525"
        >
    <Grid Name="ContentGrid">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto"/>
            <ColumnDefinition/>
        </Grid.ColumnDefinitions>

        <Grid.RowDefinitions>
            <RowDefinition></RowDefinition>
            <RowDefinition></RowDefinition>
        </Grid.RowDefinitions>
        <!--Comment NavBar to see dynamic control in UI Automation tree-->
        <dxn:NavBarControl Name="asdasd">
            <dxn:NavBarControl.Groups>
                <dxn:NavBarGroup Header="asdasdasdasd" />
            </dxn:NavBarControl.Groups>
        </dxn:NavBarControl>
        <TextBox Grid.Column="1" Name="Statictb" Text="static is visible in ui automation tree" />
        <Button Grid.Row="1" Content="Create controls" Height="25"  Click="Button_Click"/>
    </Grid>
</Window>

MainWindow.xaml.cs

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        TextBox tb = new TextBox();
        Grid.SetRow(tb, 1);
        Grid.SetColumn(tb, 1);
        tb.Text = "dynamic is not visible, if NavBar here...";
        ContentGrid.Children.Add(tb);
    }
}

Edit

According to the DevExpress answer on their support site:

After a peer is created, listening of automation events may cause performance issues. We have decided to clear invocation lists of automation events to resolve it. In your specific situation, you need to disabling clearing. To do it, please set the static DevExpress.Xpf.Core.ClearAutomationEventsHelper.IsEnabled property to False in the Window constructor.

This solve the problem.

score 6 · Answer 2 · answered Jun 20 '12 at 13:23

6

My guess is that the ContentControl's automation peer should update its children with AutomationPeer.ResetChildrenCache() after the view has been changed.

AutomationPeer.InvalidatePeer() should have the same effect (in addition to other side effects) and it is supposed to be called automatically in response to the LayoutUpdated event. You might want to check that the LayoutUpdated event is raised when the view changes.

answered Jun 20 '12 at 13:23

mgronber

3,399
16
20

Thank you sooo much for this - I have been struggling for 24 hours with a kind of similar issue where `AutomationElement`s suddenly disappeared. After reading your answer I checked if the `AutomationPeer` children of a given control were re-created during `LayoutUpdated` (and they were not) - so your suggestion with calls to `ResetChildrenCache()` and `InvalidatePeer()` did the trick. Thanks again. +1. – Lasse Christiansen Jan 02 '14 at 20:57

score 1 · Answer 3 · edited May 23 '17 at 12:34

stukselbax, try to find a sequence of keystrokes (TABs, and an ENTER most likely) to click the button that enables you to see the items. it is pretty easy to send keystrokes and i can add more in here about that if that works for you. you can always establish a tab order in your application that makes the most sense for users.

------ Update on 6/20/12 --------

Have you tried double clicking a shortcut to your app on the desktop using PInvoke to see if you can see the controls when it is opened that way? Here is a link to an example here on stackoverflow:

Directing mouse events [DllImport("user32.dll")] click, double click

Another idea: some of the controls on the app I am currently automating don't show up in the tree until a mouse click occurs on them. To accomplish this without using any hardcoded coordinates, I find something in the tree which is just (above/below/etc) the place where I need to click to get the control to appear. I then get the mouse coordinates for that item and put the mouse at a small offset from there and click. Then I can find my controls in the tree. If the app is resized, moved around, etc. this will still work since the small offset is still valid.

Come to think of it. You might want to start by using Process.Start with a shortcut instead of the actual exe to see if that helps. — chrismead, Jun 21 '12 at 13:59

ContentControl is not visible when application starts via UI Automation test, but its visible when application starts by user

3 Answers3

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