[X] passing test for 18976

src/Controls/tests/Xaml.UnitTests/Issues/Maui18976.xaml

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+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+             xmlns:local="clr-namespace:Microsoft.Maui.Controls.Xaml.UnitTests"
+             x:Class="Microsoft.Maui.Controls.Xaml.UnitTests.Maui18976">
+
+    <StackLayout Padding="30,0" Spacing="25">
+        <CheckBox x:Name="checkbox"/>
+
+        <Button x:Name="button" Text="Click me">
+            <Button.Triggers>
+                <DataTrigger Binding="{Binding IsChecked, Source={x:Reference checkbox}}" Value="True" TargetType="Button">
+                    <Setter Property="IsEnabled" Value="False"/>
+                </DataTrigger>
+            </Button.Triggers>
+        </Button>    
+    </StackLayout>
+</ContentPage>

src/Controls/tests/Xaml.UnitTests/Issues/Maui18976.xaml.cs

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+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Globalization;
+using System.Linq;
+using Microsoft.Maui.ApplicationModel;
+using Microsoft.Maui.Controls.Core.UnitTests;
+using Microsoft.Maui.Controls.Shapes;
+using Microsoft.Maui.Devices;
+using Microsoft.Maui.Dispatching;
+
+using Microsoft.Maui.Graphics;
+using Microsoft.Maui.UnitTests;
+using NUnit.Framework;
+
+namespace Microsoft.Maui.Controls.Xaml.UnitTests
+{
+    public partial class Maui18976 : ContentPage
+    {
+        public Maui18976()
+        {
+            InitializeComponent();
+        }
+
+        public Maui18976(bool useCompiledXaml)
+        {
+            //this stub will be replaced at compile time
+        }
+
+        [TestFixture]
+        class Test
+        {
+            [SetUp]
+            public void Setup()
+            {
+                Application.SetCurrentApplication(new MockApplication());
+                DispatcherProvider.SetCurrent(new DispatcherProviderStub());
+            }
+
+
+            [TearDown] public void TearDown() => AppInfo.SetCurrent(null);
+
+            [Test]
+            public void DataTriggerRestoreValue([Values(false, true)] bool useCompiledXaml)
+            {
+                var page = new Maui18976(useCompiledXaml);
+                Assert.That(page.checkbox.IsChecked, Is.False);
+                Assert.That(page.button.IsEnabled, Is.True);
+
+                page.checkbox.IsChecked = true;
+                Assert.That(page.checkbox.IsChecked, Is.True);
+                Assert.That(page.button.IsEnabled, Is.False);
+
+                page.checkbox.IsChecked = false;
+                Assert.That(page.checkbox.IsChecked, Is.False);
+                Assert.That(page.button.IsEnabled, Is.True);
+            }
+        }
+    }
+}