chore: Migrate scope-based tests to declarative executor pattern

src/tests/ReactiveUI.AOTTests/AdvancedAOTTests.cs

@@ -28,7 +28,7 @@ public class AdvancedAOTTests
     [Test]
     public async Task RoutingState_Navigation_WorksInAOT()
     {
-        var routingState = new RoutingState();
+        var routingState = new RoutingState(ImmediateScheduler.Instance);
         var viewModel = new TestRoutableViewModel();
 
         // Test navigation

src/tests/ReactiveUI.Builder.Maui.Tests/ReactiveUI.Builder.Maui.Tests.csproj

@@ -8,6 +8,7 @@
   <ItemGroup>
     <ProjectReference Include="..\..\ReactiveUI.Maui\ReactiveUI.Maui.csproj" />
     <ProjectReference Include="..\..\ReactiveUI\ReactiveUI.csproj" />
+    <ProjectReference Include="..\ReactiveUI.Maui.Tests\ReactiveUI.Maui.Tests.csproj" />
   </ItemGroup>
 
   <PropertyGroup Condition="$(TargetFramework.Contains('-windows'))">
@@ -30,5 +31,9 @@
     <Using Include="System.Reactive.Linq" />
     <Using Include="System.Threading" />
     <Using Include="System.Threading.Tasks" />
+    <Using Include="ReactiveUI" />
+    <Using Include="ReactiveUI.Maui" />
+    <Using Include="TUnit.Core" />
+    <Using Include="TUnit.Core.Executors" />
   </ItemGroup>
 </Project>

src/tests/ReactiveUI.Builder.Maui.Tests/ReactiveUIBuilderMauiTests.cs

@@ -8,29 +8,18 @@
 
 using Microsoft.Maui.Dispatching;
 
+using ReactiveUI.Maui.Tests;
+
 using Splat.Builder;
 
 namespace ReactiveUI.Builder.Maui.Tests;
 
 /// <summary>
 /// Tests for ReactiveUI Builder MAUI extensions.
 /// </summary>
+[TestExecutor<MauiTestExecutor>]
 public class ReactiveUIBuilderMauiTests
 {
-    private readonly MauiTestFixture _fixture = new();
-
-    /// <summary>
-    /// Sets up the test dispatcher for MAUI controls.
-    /// </summary>
-    [Before(Test)]
-    public void Setup() => _fixture.Setup();
-
-    /// <summary>
-    /// Restores the previous dispatcher provider.
-    /// </summary>
-    [After(Test)]
-    public void Teardown() => _fixture.Teardown();
-
     /// <summary>
     /// Verifies that the WithMaui builder extension registers required MAUI services.
     /// </summary>

src/tests/ReactiveUI.Maui.Tests/MauiTestExecutor.cs

@@ -0,0 +1,61 @@
+// Copyright (c) 2025 .NET Foundation and Contributors. All rights reserved.
+// 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 full license information.
+
+using Microsoft.Maui.Dispatching;
+using TUnit.Core.Interfaces;
+
+namespace ReactiveUI.Maui.Tests;
+
+/// <summary>
+/// Test executor that provides MAUI test isolation with dispatcher setup.
+/// Sets up MAUI DispatcherProvider for test execution and restores state on cleanup.
+/// </summary>
+/// <remarks>
+/// This executor provides:
+/// - MAUI DispatcherProvider configuration for test execution
+/// - Automatic cleanup and state restoration after test completion
+/// Tests using this executor should be marked with [NotInParallel] if they modify shared state.
+/// </remarks>
+public class MauiTestExecutor : ITestExecutor
+{
+    private IDispatcherProvider? _previousProvider;
+
+    /// <inheritdoc/>
+    public virtual async ValueTask ExecuteTest(TestContext context, Func<ValueTask> testAction)
+    {
+        ArgumentNullException.ThrowIfNull(testAction);
+
+        Initialize();
+
+        try
+        {
+            await testAction();
+        }
+        finally
+        {
+            CleanUp();
+        }
+    }
+
+    /// <summary>
+    /// Initializes the MAUI test environment by setting up the test dispatcher provider.
+    /// </summary>
+    protected virtual void Initialize()
+    {
+        _previousProvider = DispatcherProvider.Current;
+        DispatcherProvider.SetCurrent(new TestDispatcherProvider());
+    }
+
+    /// <summary>
+    /// Cleans up the MAUI test environment by restoring the previous dispatcher provider.
+    /// </summary>
+    protected virtual void CleanUp()
+    {
+        if (_previousProvider is not null)
+        {
+            DispatcherProvider.SetCurrent(_previousProvider);
+        }
+    }
+}

src/tests/ReactiveUI.Maui.Tests/ReactiveCarouselViewTests.cs

@@ -8,22 +8,9 @@ namespace ReactiveUI.Maui.Tests;
 /// <summary>
 /// Tests for ReactiveCarouselView.
 /// </summary>
+[TestExecutor<MauiTestExecutor>]
 public class ReactiveCarouselViewTests
 {
-    private readonly MauiTestFixture _fixture = new();
-
-    /// <summary>
-    /// Sets up the test dispatcher for MAUI controls.
-    /// </summary>
-    [Before(Test)]
-    public void Setup() => _fixture.Setup();
-
-    /// <summary>
-    /// Restores the previous dispatcher provider.
-    /// </summary>
-    [After(Test)]
-    public void Teardown() => _fixture.Teardown();
-
     /// <summary>
     /// Tests that ViewModel property can be set and retrieved.
     /// </summary>

src/tests/ReactiveUI.Maui.Tests/ReactiveContentPageTests.cs

@@ -8,22 +8,9 @@ namespace ReactiveUI.Maui.Tests;
 /// <summary>
 /// Tests for ReactiveContentPage.
 /// </summary>
+[TestExecutor<MauiTestExecutor>]
 public class ReactiveContentPageTests
 {
-    private readonly MauiTestFixture _fixture = new();
-
-    /// <summary>
-    /// Sets up the test dispatcher for MAUI controls.
-    /// </summary>
-    [Before(Test)]
-    public void Setup() => _fixture.Setup();
-
-    /// <summary>
-    /// Restores the previous dispatcher provider.
-    /// </summary>
-    [After(Test)]
-    public void Teardown() => _fixture.Teardown();
-
     /// <summary>
     /// Tests that ViewModel property can be set and retrieved.
     /// </summary>

src/tests/ReactiveUI.Maui.Tests/ReactiveContentViewTests.cs

@@ -8,22 +8,9 @@ namespace ReactiveUI.Maui.Tests;
 /// <summary>
 /// Tests for ReactiveContentView.
 /// </summary>
+[TestExecutor<MauiTestExecutor>]
 public class ReactiveContentViewTests
 {
-    private readonly MauiTestFixture _fixture = new();
-
-    /// <summary>
-    /// Sets up the test dispatcher for MAUI controls.
-    /// </summary>
-    [Before(Test)]
-    public void Setup() => _fixture.Setup();
-
-    /// <summary>
-    /// Restores the previous dispatcher provider.
-    /// </summary>
-    [After(Test)]
-    public void Teardown() => _fixture.Teardown();
-
     /// <summary>
     /// Tests that ViewModel property can be set and retrieved.
     /// </summary>

src/tests/ReactiveUI.Maui.Tests/ReactiveFlyoutPageTests.cs

@@ -8,22 +8,9 @@ namespace ReactiveUI.Maui.Tests;
 /// <summary>
 /// Tests for ReactiveFlyoutPage.
 /// </summary>
+[TestExecutor<MauiTestExecutor>]
 public class ReactiveFlyoutPageTests
 {
-    private readonly MauiTestFixture _fixture = new();
-
-    /// <summary>
-    /// Sets up the test dispatcher for MAUI controls.
-    /// </summary>
-    [Before(Test)]
-    public void Setup() => _fixture.Setup();
-
-    /// <summary>
-    /// Restores the previous dispatcher provider.
-    /// </summary>
-    [After(Test)]
-    public void Teardown() => _fixture.Teardown();
-
     /// <summary>
     /// Tests that ViewModel property can be set and retrieved.
     /// </summary>

src/tests/ReactiveUI.Maui.Tests/ReactiveImageItemViewTests.cs

@@ -8,22 +8,9 @@ namespace ReactiveUI.Maui.Tests;
 /// <summary>
 /// Tests for ReactiveImageItemView.
 /// </summary>
+[TestExecutor<MauiTestExecutor>]
 public class ReactiveImageItemViewTests
 {
-    private readonly MauiTestFixture _fixture = new();
-
-    /// <summary>
-    /// Sets up the test dispatcher for MAUI controls.
-    /// </summary>
-    [Before(Test)]
-    public void Setup() => _fixture.Setup();
-
-    /// <summary>
-    /// Restores the previous dispatcher provider.
-    /// </summary>
-    [After(Test)]
-    public void Teardown() => _fixture.Teardown();
-
     /// <summary>
     /// Tests that ViewModel property can be set and retrieved.
     /// </summary>

src/tests/ReactiveUI.Maui.Tests/ReactiveMasterDetailPageTests.cs

@@ -8,22 +8,9 @@ namespace ReactiveUI.Maui.Tests;
 /// <summary>
 /// Tests for ReactiveMasterDetailPage.
 /// </summary>
+[TestExecutor<MauiTestExecutor>]
 public class ReactiveMasterDetailPageTests
 {
-    private readonly MauiTestFixture _fixture = new();
-
-    /// <summary>
-    /// Sets up the test dispatcher for MAUI controls.
-    /// </summary>
-    [Before(Test)]
-    public void Setup() => _fixture.Setup();
-
-    /// <summary>
-    /// Restores the previous dispatcher provider.
-    /// </summary>
-    [After(Test)]
-    public void Teardown() => _fixture.Teardown();
-
     /// <summary>
     /// Tests that ViewModel property can be set and retrieved.
     /// </summary>

src/tests/ReactiveUI.Maui.Tests/ReactiveMultiPageTests.cs

@@ -8,22 +8,9 @@ namespace ReactiveUI.Maui.Tests;
 /// <summary>
 /// Tests for ReactiveMultiPage.
 /// </summary>
+[TestExecutor<MauiTestExecutor>]
 public class ReactiveMultiPageTests
 {
-    private readonly MauiTestFixture _fixture = new();
-
-    /// <summary>
-    /// Sets up the test dispatcher for MAUI controls.
-    /// </summary>
-    [Before(Test)]
-    public void Setup() => _fixture.Setup();
-
-    /// <summary>
-    /// Restores the previous dispatcher provider.
-    /// </summary>
-    [After(Test)]
-    public void Teardown() => _fixture.Teardown();
-
     /// <summary>
     /// Tests that ViewModel property can be set and retrieved.
     /// </summary>

src/tests/ReactiveUI.Maui.Tests/ReactiveNavigationPageTests.cs

@@ -8,22 +8,9 @@ namespace ReactiveUI.Maui.Tests;
 /// <summary>
 /// Tests for ReactiveNavigationPage.
 /// </summary>
+[TestExecutor<MauiTestExecutor>]
 public class ReactiveNavigationPageTests
 {
-    private readonly MauiTestFixture _fixture = new();
-
-    /// <summary>
-    /// Sets up the test dispatcher for MAUI controls.
-    /// </summary>
-    [Before(Test)]
-    public void Setup() => _fixture.Setup();
-
-    /// <summary>
-    /// Restores the previous dispatcher provider.
-    /// </summary>
-    [After(Test)]
-    public void Teardown() => _fixture.Teardown();
-
     /// <summary>
     /// Tests that ViewModel property can be set and retrieved.
     /// </summary>