ItemsRepeaterExtensions fixes (#538)

samples/Uno.Toolkit.Samples/Uno.Toolkit.Samples.Shared/App.xaml.Navigation.cs

@@ -86,7 +86,7 @@ private Shell BuildShell()
 			AddNavigationItems(nv);
 
 			// landing navigation
-			ShellNavigateTo<TabBarBehaviorSamplePage>(
+			ShellNavigateTo<RuntimeTestRunner>(
 #if WINDOWS_UWP
 				// note: on uwp, NavigationView.SelectedItem MUST be set on launch to avoid entering compact-mode
 				trySynchronizeCurrentItem: true

src/Uno.Toolkit.RuntimeTests/Tests/ItemsRepeaterChipTests.cs

@@ -146,7 +146,7 @@ public async Task MultiToSingle_Selected_ShouldPreserveFirstSelection()
 
 	#endregion
 
-	private static ItemsRepeater SetupItemsRepeater(object source, ItemsSelectionMode mode)
+	internal static ItemsRepeater SetupItemsRepeater(object source, ItemsSelectionMode mode)
 	{
 		var SUT = new ItemsRepeater
 		{
@@ -162,22 +162,22 @@ private static ItemsRepeater SetupItemsRepeater(object source, ItemsSelectionMod
 		return SUT;
 	}
 
-	private static bool? IsChipSelectedAt(ItemsRepeater ir, int index)
+	internal static bool? IsChipSelectedAt(ItemsRepeater ir, int index)
 	{
 		return (ir.TryGetElement(index) as ChipControl)?.IsChecked;
 	}
 
 	// since we are not using IsThreeState=True, the values can only be true/false.
 	// if any of them is null, that means there is another problem and should be thrown.
 	// therefore, only == check should be used in an assertion.
-	private static bool?[] GetChipsSelectionState(ItemsRepeater ir)
+	internal static bool?[] GetChipsSelectionState(ItemsRepeater ir)
 	{
 		return (ir.ItemsSource as IEnumerable)?.Cast<object>()
 			.Select((_, i) => (ir.TryGetElement(i) as ChipControl)?.IsChecked)
 			.ToArray() ?? new bool?[0];
 	}
 
-	private static void FakeTapItemAt(ItemsRepeater ir, int index)
+	internal static void FakeTapItemAt(ItemsRepeater ir, int index)
 	{
 		if (ir.TryGetElement(index) is { } element)
 		{

src/Uno.Toolkit.RuntimeTests/Tests/ItemsRepeaterExtensionTests.cs

@@ -0,0 +1,43 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Windows.UI.Xaml;
+using Uno.Toolkit.RuntimeTests.Helpers;
+using Uno.Toolkit.UI;
+using Uno.UI.RuntimeTests;
+using ItemsRepeater = Microsoft.UI.Xaml.Controls.ItemsRepeater;
+using static Uno.Toolkit.RuntimeTests.Tests.ItemsRepeaterChipTests; // to borrow helper methods
+
+namespace Uno.Toolkit.RuntimeTests.Tests;
+
+[TestClass]
+[RunsOnUIThread]
+internal class ItemsRepeaterExtensionTests
+{
+	[TestMethod]
+	[DataRow(nameof(ItemsRepeaterExtensions.SelectedItemProperty))]
+	[DataRow(nameof(ItemsRepeaterExtensions.SelectedItemsProperty))]
+	[DataRow(nameof(ItemsRepeaterExtensions.SelectedIndexProperty))]
+	[DataRow(nameof(ItemsRepeaterExtensions.SelectedIndexesProperty))]
+	public async Task When_Selection_Property_Changed(string property)
+	{
+		var source = Enumerable.Range(0, 3).ToList();
+		var SUT = SetupItemsRepeater(source, ItemsSelectionMode.SingleOrNone);
+		await UnitTestUIContentHelperEx.SetContentAndWait(SUT);
+
+		(property switch
+		{
+			nameof(ItemsRepeaterExtensions.SelectedItemProperty) => () => ItemsRepeaterExtensions.SetSelectedItem(SUT, source.ElementAt(1)),
+			nameof(ItemsRepeaterExtensions.SelectedItemsProperty) => () => ItemsRepeaterExtensions.SetSelectedItems(SUT, new object[] { 1 }),
+			nameof(ItemsRepeaterExtensions.SelectedIndexProperty) => () => ItemsRepeaterExtensions.SetSelectedIndex(SUT, 1),
+			nameof(ItemsRepeaterExtensions.SelectedIndexesProperty) => () => ItemsRepeaterExtensions.SetSelectedIndexes(SUT, new int[] { 1 }),
+
+			_ => default(Action) ?? throw new ArgumentOutOfRangeException(property),
+		})();
+		Assert.AreEqual(true, IsChipSelectedAt(SUT, 1));
+	}
+}

src/Uno.Toolkit.UI/Behaviors/ItemsRepeaterExtensions.cs

@@ -239,12 +239,18 @@ private static void OnSelectionStateChanged(DependencyObject sender, DependencyP
 			if (ir.ItemsSourceView is { Count: > 0 })
 			{
 				var indexes = MapStateToIndexes();
-				if (indexes.All(x => 0 <= x && x < ir.ItemsSourceView.Count))
+
+				// validate indexes are within bounds
+				var count = ir.ItemsSourceView.Count;
+				if (indexes.All(x => 0 <= x && x < count))
 				{
+					// commit selection change
 					SetSelectionStates(ir, indexes);
+					SynchronizeMaterializedElementsSelection(ir);
 				}
 				else
 				{
+					// rollback
 					ir.SetValue(e.Property, e.OldValue);
 				}
 			}
@@ -264,7 +270,7 @@ int[] MapStateToIndexes()
 			{
 				if (e.NewValue == null) return Array.Empty<int>();
 
-				var selectedItems = e.Property == SelectedItemsProperty
+				var selectedItems = e.Property == SelectedItemProperty
 					? new[] { e.NewValue }
 					: (IList<object>)e.NewValue;