Bring over initial test cases for Input Injector in order to be able to test Sizer controls

See: CommunityToolkit/Labs-Windows#183
And Tooling Branch: https://github.com/CommunityToolkit/Tooling-Windows-Submodule/tree/llama/input-injection-2025
TODO: More fluent API surface and figuring out how to do a Drag operation instead of just Click... 😅

Author: michael-hawker

components/Sizers/src/SizerBase.xaml

@@ -46,7 +46,11 @@
     <x:Double x:Key="SizerBaseThumbRadius">2</x:Double>
     <Thickness x:Key="SizerBasePadding">4</Thickness>
 
-    <Style TargetType="controls:SizerBase">
+    <Style BasedOn="{StaticResource DefaultSizerBaseStyle}"
+           TargetType="controls:SizerBase" />
+
+    <Style x:Key="DefaultSizerBaseStyle"
+           TargetType="controls:SizerBase">
         <Setter Property="IsTabStop" Value="True" />
         <Setter Property="UseSystemFocusVisuals" Value="True" />
         <Setter Property="HorizontalAlignment" Value="Stretch" />

components/Sizers/tests/SizerInputTestClass.cs

@@ -0,0 +1,60 @@
+// 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 CommunityToolkit.WinUI.Controls;
+using CommunityToolkit.Tooling.TestGen;
+using CommunityToolkit.Tests;
+using CommunityToolkit.WinUI.Controls.Automation.Peers;
+using CommunityToolkit.Tests.Input;
+
+namespace SizersTests;
+
+[TestClass]
+public partial class SizerInputTestClass : VisualUITestBase
+{
+    [UIThreadTestMethod]
+    public void PropertySizer_TestTouchDrag(PropertySizerTestInitialBinding testControl)
+    {
+        var propertySizer = testControl.FindDescendant<PropertySizer>();
+
+        Assert.IsNotNull(propertySizer, "Could not find PropertySizer control.");
+        Assert.IsNotNull(App.ContentRoot, "Could not find ContentRoot.");
+        // Set in XAML Page LINK: PropertySizerTestInitialBinding.xaml#L14
+        Assert.AreEqual(300, propertySizer.Binding, "Property Sizer not at expected initial value.");
+
+        var location = App.ContentRoot.CoordinatesToCenter(propertySizer);
+
+        App.CurrentWindow.InjectInput();
+    }
+
+    [UIThreadTestMethod]
+    public async Task InputInjection_TestClickButton(TouchInjectionTest testControl)
+    {
+        var button = testControl.FindDescendant<Button>();
+
+        Assert.IsNotNull(button, "Could not find button control.");
+        Assert.IsFalse(testControl.WasButtonClicked, "Initial state unexpected. Button shouldn't be clicked yet.");
+
+        // Get location to button.
+        var location = App.ContentRoot!.CoordinatesToCenter(button); // TODO: Write a `CoordinatesToCenter` helper?
+
+        InputSimulator sim = App.CurrentWindow.InjectInput();
+
+        sim.StartTouch();
+        // Offset location slightly to ensure we're inside the button.
+        var pointerId = sim.TouchDown(new Point(location.X, location.Y));
+        await Task.Delay(50);
+        sim.TouchUp(pointerId);
+
+        // Ensure UI event is processed by our button
+        await CompositionTargetHelper.ExecuteAfterCompositionRenderingAsync(() => { });
+
+        // Optional delay for us to be able to see button content change before test shuts down.
+        await Task.Delay(250);
+
+        Assert.IsTrue(testControl.WasButtonClicked, "Button wasn't clicked.");
+
+        sim.StopTouch();
+    }
+}

components/Sizers/tests/Sizers.Tests.projitems

@@ -12,10 +12,14 @@
     <Compile Include="$(MSBuildThisFileDirectory)ContentSizerTestInitialLayout.xaml.cs">
       <DependentUpon>ContentSizerTestInitialLayout.xaml</DependentUpon>
     </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)SizerInputTestClass.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)ExampleSizerBaseTestClass.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)PropertySizerTestInitialBinding.xaml.cs">
       <DependentUpon>PropertySizerTestInitialBinding.xaml</DependentUpon>
     </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)TouchInjectionTest.xaml.cs">
+      <DependentUpon>TouchInjectionTest.xaml</DependentUpon>
+    </Compile>
   </ItemGroup>
   <ItemGroup>
     <Page Include="$(MSBuildThisFileDirectory)ContentSizerTestInitialLayout.xaml">
@@ -26,5 +30,9 @@
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
     </Page>
+    <Page Include="$(MSBuildThisFileDirectory)TouchInjectionTest.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:Compile</Generator>
+    </Page>
   </ItemGroup>
 </Project>

components/Sizers/tests/TouchInjectionTest.xaml

@@ -0,0 +1,19 @@
+<Page
+    x:Class="SizersTests.TouchInjectionTest"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:local="using:SizersTests"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    mc:Ignorable="d"
+    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
+
+    <Grid>
+        <Button x:Name="TestButton"
+                Width="100"
+                Height="50"
+                Margin="100,100,0,0"
+                Click="TestButton_Click"
+                Content="Not Clicked" />
+    </Grid>
+</Page>

components/Sizers/tests/TouchInjectionTest.xaml.cs

@@ -0,0 +1,41 @@
+// 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 Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Controls.Primitives;
+using Microsoft.UI.Xaml.Data;
+using Microsoft.UI.Xaml.Input;
+using Microsoft.UI.Xaml.Media;
+using Microsoft.UI.Xaml.Navigation;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Runtime.InteropServices.WindowsRuntime;
+using Windows.Foundation;
+using Windows.Foundation.Collections;
+
+// The Blank Page item template is documented at https://go.microsoft.com/fwlink/?LinkId=234238
+
+namespace SizersTests;
+/// <summary>
+/// An empty page that can be used on its own or navigated to within a Frame.
+/// </summary>
+public sealed partial class TouchInjectionTest : Page
+{
+    public bool WasButtonClicked { get; set; }
+
+    public TouchInjectionTest()
+    {
+        this.InitializeComponent();
+    }
+
+    private void TestButton_Click(object sender, RoutedEventArgs args)
+    {
+        WasButtonClicked = true;
+
+        TestButton.Content = "Clicked!";
+    }
+}