FlaUI WPF Element Discovery

FlaUI WPF Element Discovery

When automating WPF applications with FlaUI, elements you expect to find may be missing from the UIA automation tree. This skill covers the most common causes and their fixes, based on how WPF exposes elements to UI Automation.

Problem 1: AutomationId Set But Not Visible in UIA

Setting AutomationProperties.AutomationId on a content element inside an ItemsControl may not expose it in the UIA tree. The UIA tree reflects the items container, not the content template.

Symptoms:

• designer.FindAllDescendants(cf => cf.ByAutomationId("MyNode")) returns empty
• The AutomationId is correctly set in XAML via AutomationProperties.AutomationId="{Binding Name}"
• The element is visually present and interactive

Root cause: In WPF's ItemsControl pattern (e.g., Nodify's NodifyEditor), items are wrapped in containers (ItemContainer, ListBoxItem, TreeViewItem). The UIA tree exposes these containers, not the content templates inside them. Setting AutomationId on a DataTemplate child (e.g., nodify:Node) places it below the container level where UIA may not propagate it.

Fix — set AutomationId on the ItemContainerStyle, not the DataTemplate:

<!-- WRONG: AutomationId on content element inside DataTemplate -->
<DataTemplate DataType="{x:Type local:MyItem}">
    <nodify:Node AutomationProperties.AutomationId="{Binding Name}" .../>
</DataTemplate>

<!-- RIGHT: AutomationId on the items container via Style -->
<Style x:Key="NodeStyle" TargetType="{x:Type nodify:ItemContainer}">
    <Setter Property="AutomationProperties.AutomationId" Value="{Binding Name}"/>
    <Setter Property="Location" Value="{Binding PixelPosition, Mode=TwoWay}"/>
</Style>

This applies to any ItemsControl-based pattern: ListView, ListBox, TreeView, NodifyEditor, etc.

Problem 2: FindAllDescendants Missing Deeply Nested Children

node.FindAllDescendants() may not return all elements in the visual tree. TextBlocks or other elements inside nested ItemsControl containers can be omitted.

Symptoms:

• A node element is found, but searching its descendants for a specific child returns null
• The child element IS visible when searching from the designer (root) level
• The child's parent ItemsControlItem IS found as a descendant, but the child itself is not

Example: Nodify output connector structure:

ItemContainer (node)                  ← FindAllDescendants() starts here
  └── ItemsControl (PART_Output)     ← found
       └── ItemsControlItem          ← found
            └── TextBlock "ZMap3D"   ← NOT found in node.FindAllDescendants()

Fix — search children of the specific container directly:

// FindAllDescendants misses deeply nested TextBlocks
AutomationElement? socketTextBlock = null;

// First try: search all descendants (works for shallow elements)
foreach (var desc in node.FindAllDescendants())
{
    if (desc.Name?.StartsWith(socketName + "\n") == true)
    {
        socketTextBlock = desc;
        break;
    }
}

// If not found: search children of each ItemsControlItem directly
if (socketTextBlock is null)
{
    foreach (var desc in node.FindAllDescendants())
    {
        if (desc.Properties.ClassName.ValueOrDefault != "ItemsControlItem")
        {
            continue;
        }

        // FindAllChildren goes one level deep — catches elements
        // that FindAllDescendants missed
        var children = desc.FindAllChildren();
        foreach (var child in children)
        {
            if (child.Name?.StartsWith(socketName + "\n") == true)
            {
                socketTextBlock = child;
                break;
            }
        }

        if (socketTextBlock is not null)
        {
            break;
        }
    }
}

Problem 3: Shape-Based Controls Not Visible in UIA Tree

WPF controls inheriting from Shape (Path, Ellipse, Rectangle, Line, and custom shapes) do not provide an AutomationPeer by default. They are invisible to FlaUI's FindAllDescendants().

Affected controls:

• Nodify's BaseConnection / MidpointConnection (extends Shape)
• Custom drawing elements extending Shape
• Path elements used for connection lines

Symptoms:

• After creating connections between nodes, no Connection elements appear in FindAllDescendants()
• ClassName.Contains("Connection") or ClassName.Contains("Path") finds nothing
• The connections are visually present and interactive via mouse

Impact on testing:

• Connection existence cannot be verified through UIA element inspection
• FindAllDescendants().Length may decrease after connecting (connector structure changes)
• Do not rely on element count comparison for connection verification

Workarounds:

1. Accept that connections can't be verified via UIA. Document this limitation and verify connections indirectly (e.g., the drag operation completed without error).

2. Add a custom AutomationPeer to the connection control if you control the source code:

public class MidpointConnection : BaseConnection
{
    protected override AutomationPeer OnCreateAutomationPeer()
    {
        return new FrameworkElementAutomationPeer(this);
    }
}

3. Expose connection count as an AutomationProperty on a parent element that IS visible in UIA.

Quick Reference

Situation	Solution
ByAutomationId finds nothing	Set AutomationId on the ItemContainerStyle, not on DataTemplate content
TextBlock missing from FindAllDescendants	Use FindAllChildren() on the parent ItemsControlItem directly
Connection/Path not in UIA tree	Shape-based controls have no AutomationPeer — invisible to UIA
Element count decreases after action	Connector structure can change on connection — don't rely on count comparison
Need to distinguish input/output connectors	Filter ItemsControlItem by position (left half = input, right half = output)

Diagnostic: Dump UIA Tree

When elements aren't found, dump the full UIA tree to see what's actually exposed:

var allDescs = designer.FindAllDescendants();
Console.WriteLine($"Total elements: {allDescs.Length}");
foreach (var desc in allDescs)
{
    var cls = desc.Properties.ClassName.ValueOrDefault ?? "(null)";
    var name = desc.Name ?? "(null)";
    var aid = desc.Properties.AutomationId.ValueOrDefault ?? "";
    var b = desc.BoundingRectangle;
    Console.WriteLine(
        $"  [{cls}] Name=\"{name}\" AutomationId=\"{aid}\" " +
        $"Bounds=({b.Left},{b.Top},{b.Width}x{b.Height})");
}

Check for:

• AutomationId — is it on the expected element or its container?
• ClassName — ItemsControlItem vs the control type you expect
• Missing elements — compare with what you see visually