Fix TreeListViewItems IsExpanded bug

When IsExpanded is data bound and the bound object defaults to true, the TreeListViewItem will now properly start in an expanded state.
Fix issue with referencing the TreeListView from UI Automation by adding in a new AutomationPeer.
Fixed issue with UI Test artifacts location on pipeline.

Author: Keboo

.github/workflows/build_artifacts.yml

@@ -56,7 +56,7 @@ jobs:
         uses: actions/upload-artifact@v3
         with:
           name: Screenshots-${{ github.run_number }}
-          path: ${{ github.workspace }}\MaterialDesignThemes.UITests\bin\${{ inputs.build-configuration }}\net8.0-windows\Screenshots
+          path: ${{ github.workspace }}\MaterialDesignThemes.UITests\bin\${{ inputs.build-configuration }}\net8.0-windows7\Screenshots
           if-no-files-found: ignore
 
       - name: Build NuGets

Directory.packages.props

@@ -26,7 +26,7 @@
     <PackageVersion Include="System.Net.Http" Version="4.3.4" />
     <PackageVersion Include="System.Text.RegularExpressions" Version="4.3.1" />
     <PackageVersion Include="VirtualizingWrapPanel" Version="1.5.8" />
-    <PackageVersion Include="XAMLTest" Version="1.2.0" />
+    <PackageVersion Include="XAMLTest" Version="1.2.1" />
     <PackageVersion Include="xunit" Version="2.6.2" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.5.4" />
     <PackageVersion Include="Xunit.StaFact" Version="1.1.11" />

MaterialDesignThemes.UITests/TestBase.cs

@@ -50,7 +50,9 @@ protected async Task<IVisualElement> LoadUserControl(Type userControlType)
     public async Task InitializeAsync() =>
         App = await XamlTest.App.StartRemote(new AppOptions
         {
+#if !DEBUG
             MinimizeOtherWindows = !Debugger.IsAttached,
+#endif
             AllowVisualStudioDebuggerAttach = AttachedDebuggerToRemoteProcess,
             LogMessage = Output.WriteLine
         });

MaterialDesignThemes.UITests/WPF/TreeListViews/TreeItem.cs

@@ -1,12 +1,16 @@
 using System.ComponentModel;
 using System.Diagnostics;
 using System.Windows.Data;
+using CommunityToolkit.Mvvm.ComponentModel;
 
 namespace MaterialDesignThemes.UITests.WPF.TreeListViews;
 
 [DebuggerDisplay("{Value} (Children: {Children.Count})")]
-public class TreeItem
+public partial class TreeItem : ObservableObject
 {
+    [ObservableProperty]
+    private bool _isExpanded;
+
     public string Value { get; }
 
     public TreeItem? Parent { get; }

MaterialDesignThemes.UITests/WPF/TreeListViews/TreeListViewDataBinding.xaml

@@ -22,9 +22,15 @@
           <TextBlock Text="{Binding Value}" />
         </HierarchicalDataTemplate>
       </materialDesign:TreeListView.ItemTemplate>
+      <materialDesign:TreeListView.ItemContainerStyle>
+        <Style TargetType="materialDesign:TreeListViewItem" BasedOn="{StaticResource {x:Type materialDesign:TreeListViewItem}}">
+          <Setter Property="IsExpanded" Value="{Binding IsExpanded}" />
+        </Style>
+      </materialDesign:TreeListView.ItemContainerStyle>
     </materialDesign:TreeListView>
     <StackPanel Grid.Row="1" Orientation="Horizontal">
       <Button Content="Add" Click="Add_OnClick" />
+      <Button Content="Add with Children" Click="AddWithChildren_OnClick" />
       <Button Content="Remove" Click="Remove_OnClick" />
       <Button Content="Replace" Click="Replace_OnClick" />
       <Button Content="Down" Click="MoveDown_OnClick" />

MaterialDesignThemes.UITests/WPF/TreeListViews/TreeListViewDataBinding.xaml.cs

@@ -19,6 +19,7 @@ public TreeListViewDataBinding()
     }
 
     public void Add_OnClick(object sender, EventArgs e) => AddItem();
+    public void AddWithChildren_OnClick(object sender, EventArgs e) => AddItemWithChildren();
 
     private void AddItem()
     {
@@ -32,6 +33,18 @@ private void AddItem()
         }
     }
 
+    private void AddItemWithChildren()
+    {
+        TreeItem parent = new(Items.Count.ToString(), null)
+        {
+            IsExpanded = true
+        };
+        parent.Children.Add(new TreeItem(parent.Value + "_0", parent));
+        parent.Children.Add(new TreeItem(parent.Value + "_1", parent));
+        parent.Children.Add(new TreeItem(parent.Value + "_2", parent));
+        Items.Add(parent);
+    }
+
     public void Remove_OnClick(object sender, EventArgs e)
     {
         if (TreeListView.SelectedItem is TreeItem selectedItem)
@@ -40,12 +53,9 @@ public void Remove_OnClick(object sender, EventArgs e)
         }
     }
 
-    private void RemoveItem(IList<TreeItem> items, TreeItem toRemove)
+    private static void RemoveItem(IList<TreeItem> items, TreeItem toRemove)
     {
-        if (items.Contains(toRemove))
-        {
-            items.Remove(toRemove);
-        }
+        items.Remove(toRemove);
         foreach (TreeItem item in items)
         {
             RemoveItem(item.Children, toRemove);

MaterialDesignThemes.UITests/WPF/TreeListViews/TreeListViewTests.cs

@@ -7,7 +7,7 @@ public class TreeListViewTests : TestBase
     public TreeListViewTests(ITestOutputHelper output)
         : base(output)
     {
-        AttachedDebuggerToRemoteProcess = false;
+        AttachedDebuggerToRemoteProcess = true;
     }
 
     public static IEnumerable<object[]> GetTestControls()
@@ -74,7 +74,12 @@ await Wait.For(async () =>
         {
             childElement = await treeListView.GetElement<TreeListViewItem>("/TreeListViewItem[3]");
             await childElement.LeftClick();
-            return await childElement.GetIsSelected();
+            bool isSelected = await childElement.GetIsSelected();
+            if (!isSelected)
+            {
+                await Task.Delay(MouseInput.GetDoubleClickTime);
+            }
+            return isSelected;
         });
         await moveDownButton.LeftClick();
 
@@ -112,7 +117,12 @@ await Wait.For(async () =>
         {
             childElement = await treeListView.GetElement<TreeListViewItem>("/TreeListViewItem[3]");
             await childElement.LeftClick();
-            return await childElement.GetIsSelected();
+            bool isSelected = await childElement.GetIsSelected();
+            if (!isSelected)
+            {
+                await Task.Delay(MouseInput.GetDoubleClickTime);
+            }
+            return isSelected;
         });
         await moveUpButton.LeftClick();
 
@@ -985,6 +995,28 @@ public async Task TreeListView_WithCollectionView_RendersItems()
         recorder.Success();
     }
 
+    [Fact]
+    public async Task TreeListView_AddingExpandedItemWithChildren_ShowsExpanedItem()
+    {
+        await using var recorder = new TestRecorder(App);
+
+        IVisualElement<Grid> root = (await LoadUserControl<TreeListViewDataBinding>()).As<Grid>();
+        IVisualElement<TreeListView> treeListView = await root.GetElement<TreeListView>();
+        IVisualElement<Button> addWithChildrenButton = await root.GetElement(ElementQuery.PropertyExpression<Button>(x => x.Content, "Add with Children"));
+
+        await addWithChildrenButton.LeftClick();
+
+        await AssertTreeItemContent(treeListView, 0, "0");
+        await AssertTreeItemContent(treeListView, 1, "1");
+        await AssertTreeItemContent(treeListView, 2, "2");
+        await AssertTreeItemContent(treeListView, 3, "3", true);
+        await AssertTreeItemContent(treeListView, 4, "3_0");
+        await AssertTreeItemContent(treeListView, 5, "3_1");
+        await AssertTreeItemContent(treeListView, 6, "3_2");
+
+        recorder.Success();
+    }
+
     private static async Task AssertTreeItemContent(IVisualElement<TreeListView> treeListView, int index, string content, bool isExpanded = false)
     {
         await Wait.For(async () =>

MaterialDesignThemes.Wpf/Automation/Peers/TreeListViewItemAutomationPeer.cs

@@ -0,0 +1,30 @@
+using System.Windows.Automation.Peers;
+
+namespace MaterialDesignThemes.Wpf.Automation.Peers;
+
+public class TreeListViewAutomationPeer : ListViewAutomationPeer
+{
+    public TreeListViewAutomationPeer(TreeListView owner) : base(owner)
+    {
+    }
+
+    protected override ItemAutomationPeer CreateItemAutomationPeer(object item)
+        => new TreeListViewItemAutomationPeer(item, this);
+}
+
+public class TreeListViewItemAutomationPeer : ListBoxItemAutomationPeer
+{
+    public TreeListViewItemAutomationPeer(object owner, SelectorAutomationPeer selectorAutomationPeer)
+        : base(owner, selectorAutomationPeer)
+    {
+    }
+
+    public override object GetPattern(PatternInterface patternInterface)
+    {
+        if (patternInterface == PatternInterface.ExpandCollapse)
+        {
+            return this;
+        }
+        return base.GetPattern(patternInterface);
+    }
+}

MaterialDesignThemes.Wpf/Internal/TreeListViewItemsCollection.cs

@@ -58,6 +58,9 @@ public int GetLevel(int index)
     public bool GetIsExpanded(int index)
         => ItemIsExpanded[index];
 
+    public void SetIsExpanded(int index, bool isExpanded)
+        => ItemIsExpanded[index] = isExpanded;
+
     public void InsertWithLevel(int index, object? item, int level)
     {
         if (level < 0) throw new ArgumentOutOfRangeException(nameof(level), level, "Item level must not be negative");
@@ -138,9 +141,7 @@ protected override void InsertItem(int index, object? item)
     }
 
     protected override void MoveItem(int oldIndex, int newIndex)
-    {
-        MoveOffsetAdjustedItem(oldIndex, newIndex);
-    }
+        => MoveOffsetAdjustedItem(oldIndex, newIndex);
 
     internal void MoveOffsetAdjustedItem(int oldIndex, int newIndex)
     {
@@ -281,7 +282,7 @@ int GetAbsoluteIndex(int relativeIndex)
     }
 }
 
-internal static class ListExtensions
+file static class ListExtensions
 {
     public static void MoveItem(this IList list, int oldIndex, int newIndex)
     {
@@ -295,7 +296,6 @@ public static void MoveItem(this IList list, int oldIndex, int newIndex)
 
 public class MoveEventArgs : EventArgs
 {
-
     public int OldIndex { get; }
     public int NewIndex { get; }
 

MaterialDesignThemes.Wpf/TreeListView.cs

@@ -1,4 +1,6 @@
 using System.Collections.Specialized;
+using System.Windows.Automation.Peers;
+using MaterialDesignThemes.Wpf.Automation.Peers;
 using MaterialDesignThemes.Wpf.Internal;
 
 namespace MaterialDesignThemes.Wpf;
@@ -30,6 +32,9 @@ public TreeListView()
     {
     }
 
+    protected override AutomationPeer OnCreateAutomationPeer()
+        => new TreeListViewAutomationPeer(this);
+
     private static object? CoerceItemsSource(DependencyObject d, object? baseValue)
     {
         if (d is TreeListView treeListView)
@@ -41,7 +46,7 @@ public TreeListView()
     }
 
     protected override DependencyObject GetContainerForItemOverride()
-        => new TreeListViewItem();
+        => new TreeListViewItem(this);
 
     protected override bool IsItemItsOwnContainerOverride(object? item)
         => item is TreeListViewItem;
@@ -80,7 +85,9 @@ internal void ItemExpandedChanged(TreeListViewItem item)
         {
             int index = ItemContainerGenerator.IndexFromContainer(item);
             var children = item.GetChildren().ToList();
-            if (item.IsExpanded)
+            bool isExpanded = item.IsExpanded;
+            itemsSource.SetIsExpanded(index, isExpanded);
+            if (isExpanded)
             {
                 int parentLevel = itemsSource.GetLevel(index);
                 for (int i = 0; i < children.Count; i++)