Merge pull request #6080 from unoplatform/dev/djo/treeview-fix

fix(treeview): Fix error when items of last nested item are cleared

src/Uno.UI.RuntimeTests/Tests/Microsoft_UI_Xaml_Controls/Given_TreeView.cs

@@ -0,0 +1,120 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Private.Infrastructure;
+using Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Controls.ListViewPages;
+#if NETFX_CORE
+using Uno.UI.Extensions;
+#elif __IOS__
+using UIKit;
+#elif __MACOS__
+using AppKit;
+#else
+using Uno.UI;
+#endif
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Controls.Primitives;
+using static Private.Infrastructure.TestServices;
+using Windows.Foundation;
+using Windows.UI;
+using Windows.UI.Xaml.Media;
+using FluentAssertions;
+using FluentAssertions.Execution;
+using Uno.Extensions;
+using Uno.UI.RuntimeTests.Helpers;
+using System.ComponentModel;
+using Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Controls;
+
+namespace Uno.UI.RuntimeTests.Tests.Microsoft_UI_Xaml_Controls
+{
+	[TestClass]
+	[RunsOnUIThread]
+	public partial class Given_TreeView
+	{
+		private ResourceDictionary _testsResources;
+
+		private DataTemplate TreeViewItemTemplate => _testsResources["TreeViewItemTemplate"] as DataTemplate;
+
+		[TestInitialize]
+		public void Init()
+		{
+			_testsResources = new TestsResources();
+		}
+
+		[TestMethod]
+		public async Task When_Sublist_Of_Last_Item_Cleared()
+		{
+			var initial_Depth_0 = 0;
+			var initial_Depth_1 = 64;
+			var initial_Depth_2 = 96;
+
+			var treeView = new Microsoft.UI.Xaml.Controls.TreeView();
+			treeView.ItemTemplate = TreeViewItemTemplate;
+			var testViewModelItems = Enumerable.Range(0, 2).Select(_ => Get_Depth_0_Item()).ToArray();
+			treeView.ItemsSource = testViewModelItems;
+			WindowHelper.WindowContent = treeView;
+
+			await WindowHelper.WaitForLoaded(treeView);
+
+			await WindowHelper.WaitForNonNull(() => treeView.ContainerFromItem(testViewModelItems.Last().Items.First().Items.Last()));
+
+			var currentItem = testViewModelItems.First().Items.Last().Items.First();
+
+			Assert.IsNotNull(treeView.ContainerFromItem(currentItem));
+
+			testViewModelItems.First().Items.Last().Items.Clear();
+
+			await WindowHelper.WaitFor(() => treeView.ContainerFromItem(currentItem) == null);
+
+			TestViewModelItem Get_Depth_0_Item() => new TestViewModelItem
+			{
+				Label = $"Item {++initial_Depth_0}",
+				Items =
+				{
+					Get_Depth_1_Item(),
+					Get_Depth_1_Item(),
+					Get_Depth_1_Item(),
+				}
+			};
+
+			TestViewModelItem Get_Depth_1_Item() => new TestViewModelItem
+			{
+				Label = $"Subitem {(char)(++initial_Depth_1)}",
+				Items =
+				{
+					Get_Depth_2_Item(),
+					Get_Depth_2_Item(),
+				}
+			};
+			TestViewModelItem Get_Depth_2_Item() => new TestViewModelItem { Label = $"Subitem {(char)(++initial_Depth_2)}" };
+		}
+
+		public class TestViewModelItem : INotifyPropertyChanged
+		{
+			public event PropertyChangedEventHandler PropertyChanged;
+
+			public bool IsExpanded { get; set; } = true;
+
+			public ObservableCollection<TestViewModelItem> Items { get; } = new ObservableCollection<TestViewModelItem>();
+
+			public string Label
+			{
+				get { return _label; }
+				set
+				{
+					if (_label != value)
+					{
+						_label = value;
+						PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Label)));
+					}
+				}
+			}
+			string _label;
+		}
+	}
+}

src/Uno.UI.RuntimeTests/Tests/Windows_UI_Xaml_Controls/TestsResources.xaml

@@ -2,6 +2,7 @@
 					xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 					xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 					xmlns:local="using:Uno.UI.RuntimeTests.Tests.Windows_UI_Xaml_Controls"
+					xmlns:mux="using:Microsoft.UI.Xaml.Controls"
 					xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
 					xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 					mc:Ignorable="d">
@@ -167,4 +168,12 @@
 	<DataTemplate x:Key="PivotItemTemplate">
 		<TextBlock Text="{Binding Content}" />
 	</DataTemplate>
+
+	<DataTemplate x:Key="TreeViewItemTemplate">
+		<mux:TreeViewItem HorizontalContentAlignment="Left"
+						  VerticalContentAlignment="Center"
+						  Content="{Binding Path=Label}"
+						  IsExpanded="{Binding Path=IsExpanded, Mode=TwoWay}"
+						  ItemsSource="{Binding Path=Items}" />
+	</DataTemplate>
 </ResourceDictionary>

src/Uno.UI/Microsoft/UI/Xaml/Controls/TreeView/TreeViewViewModel.cs

@@ -471,7 +471,7 @@ private int IndexOfNextSibling(TreeViewNode childNode)
 			bool isLastRelativeChild = true;
 			while (parentNode != null && isLastRelativeChild)
 			{
-				int relativeIndex = parentNode.Children.IndexOf(childNode);
+				int relativeIndex = parentNode.Children.IndexOf(child);
 				if (parentNode.Children.Count - 1 != relativeIndex)
 				{
 					isLastRelativeChild = false;
@@ -485,7 +485,7 @@ private int IndexOfNextSibling(TreeViewNode childNode)
 
 			if (parentNode != null)
 			{
-				int siblingIndex = parentNode.Children.IndexOf(childNode);
+				int siblingIndex = parentNode.Children.IndexOf(child);
 				var siblingNode = parentNode.Children[siblingIndex + 1];
 				IndexOfNode(siblingNode, out stopIndex);
 			}