From 3f96aead414975c369d58eec8fed2ddb906736cc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Osman=20=C4=B0l=C3=A7ektu=C4=9F?=
 <57036326+osmanilcektu@users.noreply.github.com>
Date: Mon, 14 Sep 2026 13:52:32 +0300
Subject: [PATCH 1/2] test: cover multi-item TokenizingTextBox collection
 changes

---
 ...est_TokenizingTextBox_CollectionChanges.cs | 98 +++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 components/TokenizingTextBox/tests/Test_TokenizingTextBox_CollectionChanges.cs

diff --git a/components/TokenizingTextBox/tests/Test_TokenizingTextBox_CollectionChanges.cs b/components/TokenizingTextBox/tests/Test_TokenizingTextBox_CollectionChanges.cs
new file mode 100644
index 00000000..270ec45f
--- /dev/null
+++ b/components/TokenizingTextBox/tests/Test_TokenizingTextBox_CollectionChanges.cs
@@ -0,0 +1,98 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+using System.ComponentModel;
+using CommunityToolkit.Tests;
+using CommunityToolkit.WinUI.Controls;
+
+namespace TokenizingTextBoxTests;
+
+[TestClass]
+public class Test_TokenizingTextBox_CollectionChanges : VisualUITestBase
+{
+    [TestCategory("Test_TokenizingTextBox_CollectionChanges")]
+    [TestMethod]
+    public async Task Test_ItemsSourceRangeAdd()
+    {
+        await App.DispatcherQueue.EnqueueAsync(() =>
+        {
+            var source = new RangeObservableCollection<object> { 0, 3 };
+            var tokenBox = new TokenizingTextBox { ItemsSource = source };
+
+            source.InsertRange(1, new object[] { 1, 2 });
+
+            Assert.AreEqual(4, source.Count);
+            Assert.AreEqual(5, tokenBox.Items.Count);
+            Assert.AreEqual(0, tokenBox.Items[0]);
+            Assert.AreEqual(1, tokenBox.Items[1]);
+            Assert.AreEqual(2, tokenBox.Items[2]);
+            Assert.AreEqual(3, tokenBox.Items[3]);
+        });
+    }
+
+    [TestCategory("Test_TokenizingTextBox_CollectionChanges")]
+    [TestMethod]
+    public async Task Test_ItemsSourceRangeRemove()
+    {
+        await App.DispatcherQueue.EnqueueAsync(() =>
+        {
+            var source = new RangeObservableCollection<object> { 0, 1, 2, 3 };
+            var tokenBox = new TokenizingTextBox { ItemsSource = source };
+
+            source.RemoveRange(1, 2);
+
+            Assert.AreEqual(2, source.Count);
+            Assert.AreEqual(3, tokenBox.Items.Count);
+            Assert.AreEqual(0, tokenBox.Items[0]);
+            Assert.AreEqual(3, tokenBox.Items[1]);
+        });
+    }
+
+    private sealed class RangeObservableCollection<T> : ObservableCollection<T>
+    {
+        public void InsertRange(int index, IReadOnlyList<T> items)
+        {
+            if (items.Count == 0)
+            {
+                return;
+            }
+
+            CheckReentrancy();
+
+            var insertedItems = new List<T>(items);
+            for (var offset = 0; offset < insertedItems.Count; offset++)
+            {
+                Items.Insert(index + offset, insertedItems[offset]);
+            }
+
+            OnPropertyChanged(new PropertyChangedEventArgs(nameof(Count)));
+            OnPropertyChanged(new PropertyChangedEventArgs("Item[]"));
+            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, insertedItems, index));
+        }
+
+        public void RemoveRange(int index, int count)
+        {
+            if (count == 0)
+            {
+                return;
+            }
+
+            CheckReentrancy();
+
+            var removedItems = new List<T>(count);
+            for (var offset = 0; offset < count; offset++)
+            {
+                removedItems.Add(Items[index]);
+                Items.RemoveAt(index);
+            }
+
+            OnPropertyChanged(new PropertyChangedEventArgs(nameof(Count)));
+            OnPropertyChanged(new PropertyChangedEventArgs("Item[]"));
+            OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, removedItems, index));
+        }
+    }
+}

From 0006c60709db6d3b9db82c52534c45da408e935a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Osman=20=C4=B0l=C3=A7ektu=C4=9F?=
 <57036326+osmanilcektu@users.noreply.github.com>
Date: Mon, 14 Sep 2026 13:52:42 +0300
Subject: [PATCH 2/2] test: include TokenizingTextBox collection change tests

---
 .../TokenizingTextBox/tests/TokenizingTextBox.Tests.projitems  | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/components/TokenizingTextBox/tests/TokenizingTextBox.Tests.projitems b/components/TokenizingTextBox/tests/TokenizingTextBox.Tests.projitems
index efd6469b..66361f6b 100644
--- a/components/TokenizingTextBox/tests/TokenizingTextBox.Tests.projitems
+++ b/components/TokenizingTextBox/tests/TokenizingTextBox.Tests.projitems
@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <MSBuildAllProjects Condition="'$(MSBuildVersion)' == '' Or '$(MSBuildVersion)' &lt; '16.0'">$(MSBuildAllProjects);$(MSBuildThisFileFullPath)</MSBuildAllProjects>
@@ -11,5 +11,6 @@
   <ItemGroup>
     <Compile Include="$(MSBuildThisFileDirectory)Test_TokenizingTextBox_General.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Test_TokenizingTextBox_AutomationPeer.cs" />
+    <Compile Include="$(MSBuildThisFileDirectory)Test_TokenizingTextBox_CollectionChanges.cs" />
   </ItemGroup>
 </Project>
\ No newline at end of file