From 751ef25c45dfb2340894955601ecd4cc5f897858 Mon Sep 17 00:00:00 2001
From: Chris Pulman <chris.pulman@yahoo.com>
Date: Tue, 29 Jun 2021 05:13:01 +0100
Subject: [PATCH 1/4] feature for Xamarin added ReactiveShell, ShellViewModel,
 ReactiveFlyOut

ReactiveShell can be used when you wish to use a viewmodel on your base
NOTE: Only supports WhenActivated NOT WhenDeactivated due to the Base nature of the Shell component

ShellViewModel is a ViewModel based version of ShellContent
---
 .../ActivatingReactiveContentPageTests.cs     | 116 +++++++++
 .../Activation/Mocks/ActivatingViewModel2.cs  |  41 +++
 .../Activation/Mocks/App.xaml                 |  34 +++
 .../Activation/Mocks/App.xaml.cs              |  57 +++++
 .../Activation/Mocks/AppShell.xaml            |  39 +++
 .../Activation/Mocks/AppShell.xaml.cs         |  35 +++
 .../Activation/Mocks/ApplicationMock.cs       |  23 ++
 .../Activation/Mocks/CarouselPageView.cs      |  30 +++
 .../Activation/Mocks/CarouselPageViewModel.cs |  39 +++
 .../Activation/Mocks/ContentPageView.cs       |  31 +++
 .../Activation/Mocks/ContentPageViewModel.cs  |  41 +++
 .../Activation/Mocks/FlyOutPageViewModel.cs   |  41 +++
 .../Activation/Mocks/FlyoutPageView.xaml      |  20 ++
 .../Activation/Mocks/FlyoutPageView.xaml.cs   |  57 +++++
 .../Mocks/FlyoutPageViewDetail.xaml           |  10 +
 .../Mocks/FlyoutPageViewDetail.xaml.cs        |  26 ++
 .../Mocks/FlyoutPageViewFlyout.xaml           |  48 ++++
 .../Mocks/FlyoutPageViewFlyout.xaml.cs        |  81 ++++++
 .../Mocks/FlyoutPageViewFlyoutMenuItem.cs     |  47 ++++
 .../Activation/Mocks/MockForms.cs             | 241 ++++++++++++++++++
 .../Activation/Mocks/ShellView.cs             |  34 +++
 .../Activation/Mocks/ShellViewModel.cs        |  41 +++
 .../Activation/Mocks/TabbedPageView.cs        |  30 +++
 .../Activation/Mocks/TabbedPageViewModel.cs   |  41 +++
 .../ReactiveUI.XamForms.Tests.csproj          |  30 +++
 .../ActivationForViewFetcher.cs               |  26 ++
 src/ReactiveUI.XamForms/ReactiveFlyoutPage.cs |  55 ++++
 .../ReactiveMasterDetailPage.cs               |   2 +
 src/ReactiveUI.XamForms/ReactiveShell.cs      |  55 ++++
 src/ReactiveUI.XamForms/ShellViewModel.cs     |  89 +++++++
 30 files changed, 1460 insertions(+)
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/ActivatingReactiveContentPageTests.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/ActivatingViewModel2.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/App.xaml
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/App.xaml.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShell.xaml
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShell.xaml.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/ApplicationMock.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/CarouselPageView.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/CarouselPageViewModel.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/ContentPageView.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/ContentPageViewModel.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyOutPageViewModel.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageView.xaml
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageView.xaml.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewDetail.xaml
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewDetail.xaml.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewFlyout.xaml
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewFlyout.xaml.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewFlyoutMenuItem.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/MockForms.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/ShellView.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/ShellViewModel.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/TabbedPageView.cs
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/TabbedPageViewModel.cs
 create mode 100644 src/ReactiveUI.XamForms/ReactiveFlyoutPage.cs
 create mode 100644 src/ReactiveUI.XamForms/ReactiveShell.cs
 create mode 100644 src/ReactiveUI.XamForms/ShellViewModel.cs

diff --git a/src/ReactiveUI.XamForms.Tests/Activation/ActivatingReactiveContentPageTests.cs b/src/ReactiveUI.XamForms.Tests/Activation/ActivatingReactiveContentPageTests.cs
new file mode 100644
index 0000000000..d1db7a1b12
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/ActivatingReactiveContentPageTests.cs
@@ -0,0 +1,116 @@
+// Copyright (c) 2021 .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 System.Threading.Tasks;
+using ReactiveUI.XamForms;
+using ReactiveUI.XamForms.Tests.Activation;
+using ReactiveUI.XamForms.Tests.Activation.Mocks;
+using Splat;
+using Xamarin.Forms;
+using Xunit;
+
+namespace ReactiveUI.Tests
+{
+    /// <summary>
+    /// Tests for activating views.
+    /// </summary>
+    public class ActivatingReactiveContentPageTests
+    {
+        /// <summary>
+        /// Tests to make sure that views generally activate.
+        /// </summary>
+        [Fact]
+        public void ActivatingReactiveContentPageTest()
+        {
+            var locator = new ModernDependencyResolver();
+            locator.InitializeSplat();
+            locator.InitializeReactiveUI();
+            locator.Register(() => new ActivationForViewFetcher(), typeof(IActivationForViewFetcher));
+            locator.Register<IViewFor<ShellViewModel>>(() => new ShellView());
+            locator.Register<IViewFor<ContentPageViewModel>>(() => new ContentPageView());
+            locator.Register<IViewFor<TabbedPageViewModel>>(() => new TabbedPageView());
+            locator.Register<IViewFor<CarouselPageViewModel>>(() => new CarouselPageView());
+            locator.Register<IViewFor<FlyOutPageViewModel>>(() => new FlyoutPageView());
+
+            MockForms.Init();
+            var app = new App();
+            var main = app.MainPage as AppShell;
+
+            Assert.Equal(1, main!.ViewModel!.IsActiveCount);
+            Assert.Equal(1, main.IsActiveCount);
+
+            var vm = new ContentPageViewModel();
+            var fixture = new ContentPageView
+            {
+                ViewModel = vm
+            };
+
+            // Activate
+            main.Navigation.PushAsync(fixture);
+            Assert.Equal(1, fixture.ViewModel.IsActiveCount);
+            Assert.Equal(1, fixture.IsActiveCount);
+
+            // Deactivate
+            Shell.Current.GoToAsync("..");
+            fixture.ViewModel = null;
+            Assert.Equal(0, vm.IsActiveCount);
+            Assert.Equal(0, fixture.IsActiveCount);
+
+            var vm1 = new TabbedPageViewModel();
+            var fixture1 = new TabbedPageView
+            {
+                ViewModel = vm1
+            };
+
+            // Activate
+            main.Navigation.PushAsync(fixture1);
+            Assert.Equal(1, fixture1.ViewModel.IsActiveCount);
+            Assert.Equal(1, fixture1.IsActiveCount);
+
+            // Deactivate
+            Shell.Current.GoToAsync("..");
+            fixture1.ViewModel = null;
+            Assert.Equal(0, vm1.IsActiveCount);
+            Assert.Equal(0, fixture1.IsActiveCount);
+
+            var vm3 = new FlyOutPageViewModel();
+            var fixture3 = new FlyoutPageView
+            {
+                ViewModel = vm3
+            };
+
+            // Activate
+            main.Navigation.PushAsync(fixture3);
+            Assert.Equal(1, fixture3.ViewModel!.IsActiveCount);
+            Assert.Equal(1, fixture3.IsActiveCount);
+
+            // Deactivate
+            Shell.Current.GoToAsync("..");
+            fixture3.ViewModel = null;
+            Assert.Equal(0, vm3.IsActiveCount);
+            Assert.Equal(0, fixture3.IsActiveCount);
+
+            var vm4 = new CarouselPageViewModel();
+            var fixture4 = new CarouselPageView
+            {
+                ViewModel = vm4
+            };
+
+            // Activate
+            main.Navigation.PushAsync(fixture4);
+            Assert.Equal(1, fixture4.ViewModel!.IsActiveCount);
+            Assert.Equal(1, fixture4.IsActiveCount);
+
+            // Deactivate
+            Shell.Current.GoToAsync("..");
+            fixture4.ViewModel = null;
+            Assert.Equal(0, vm4.IsActiveCount);
+            Assert.Equal(0, fixture4.IsActiveCount);
+
+            // remember to kill the app
+            app.Quit();
+        }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ActivatingViewModel2.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ActivatingViewModel2.cs
new file mode 100644
index 0000000000..fa94722b57
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ActivatingViewModel2.cs
@@ -0,0 +1,41 @@
+// Copyright (c) 2021 .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 System.Reactive.Disposables;
+
+namespace ReactiveUI.XamForms.Tests.Activation
+{
+    /// <summary>
+    /// Activating View Model2.
+    /// </summary>
+    /// <seealso cref="ReactiveUI.ReactiveObject" />
+    /// <seealso cref="ReactiveUI.IActivatableViewModel" />
+    public class ActivatingViewModel2 : ReactiveObject, IActivatableViewModel
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ActivatingViewModel2"/> class.
+        /// </summary>
+        public ActivatingViewModel2()
+        {
+            Activator = new ViewModelActivator();
+
+            this.WhenActivated(d =>
+            {
+                IsActiveCount++;
+                d(Disposable.Create(() => IsActiveCount--));
+            });
+        }
+
+        /// <summary>
+        /// Gets or sets the Activator which will be used by the View when Activation/Deactivation occurs.
+        /// </summary>
+        public ViewModelActivator Activator { get; protected set; }
+
+        /// <summary>
+        /// Gets or sets the active count.
+        /// </summary>
+        public int IsActiveCount { get; protected set; }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/App.xaml b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/App.xaml
new file mode 100644
index 0000000000..393be06d9b
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/App.xaml
@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<test:ApplicationMock
+    x:Class="ReactiveUI.XamForms.Tests.Activation.App"
+    xmlns="http://xamarin.com/schemas/2014/forms"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    xmlns:test="clr-namespace:ReactiveUI.Tests">
+    <!--
+        Define global resources and styles here, that apply to all pages in your app.
+    -->
+    <Application.Resources>
+        <ResourceDictionary>
+            <Color x:Key="Primary">#2196F3</Color>
+            <Style TargetType="Button">
+                <Setter Property="TextColor" Value="White" />
+                <Setter Property="VisualStateManager.VisualStateGroups">
+                    <VisualStateGroupList>
+                        <VisualStateGroup x:Name="CommonStates">
+                            <VisualState x:Name="Normal">
+                                <VisualState.Setters>
+                                    <Setter Property="BackgroundColor" Value="{StaticResource Primary}" />
+                                </VisualState.Setters>
+                            </VisualState>
+                            <VisualState x:Name="Disabled">
+                                <VisualState.Setters>
+                                    <Setter Property="BackgroundColor" Value="#332196F3" />
+                                </VisualState.Setters>
+                            </VisualState>
+                        </VisualStateGroup>
+                    </VisualStateGroupList>
+                </Setter>
+            </Style>
+        </ResourceDictionary>
+    </Application.Resources>
+</test:ApplicationMock>
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/App.xaml.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/App.xaml.cs
new file mode 100644
index 0000000000..e26216449e
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/App.xaml.cs
@@ -0,0 +1,57 @@
+// Copyright (c) 2021 .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 Xamarin.Forms;
+
+namespace ReactiveUI.XamForms.Tests.Activation
+{
+    /// <summary>
+    /// The App.
+    /// </summary>
+    /// <seealso cref="Xamarin.Forms.Application" />
+    public partial class App
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="App" /> class.
+        /// </summary>
+        /// <param name="page">The page.</param>
+        public App()
+        {
+            InitializeComponent();
+
+            MainPage = new AppShell();
+        }
+
+        /// <summary>
+        /// Application developers override this method to perform actions when the application starts.
+        /// </summary>
+        /// <remarks>
+        /// To be added.
+        /// </remarks>
+        protected override void OnStart()
+        {
+        }
+
+        /// <summary>
+        /// Application developers override this method to perform actions when the application enters the sleeping state.
+        /// </summary>
+        /// <remarks>
+        /// To be added.
+        /// </remarks>
+        protected override void OnSleep()
+        {
+        }
+
+        /// <summary>
+        /// Application developers override this method to perform actions when the application resumes from a sleeping state.
+        /// </summary>
+        /// <remarks>
+        /// To be added.
+        /// </remarks>
+        protected override void OnResume()
+        {
+        }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShell.xaml b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShell.xaml
new file mode 100644
index 0000000000..18c67fc8a0
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShell.xaml
@@ -0,0 +1,39 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<rxui:ReactiveShell
+    x:Class="ReactiveUI.XamForms.Tests.Activation.AppShell"
+    xmlns="http://xamarin.com/schemas/2014/forms"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    xmlns:rxui="clr-namespace:ReactiveUI.XamForms;assembly=ReactiveUI.XamForms"
+    xmlns:vm="clr-namespace:ReactiveUI.XamForms.Tests.Activation"
+    Title="Shell.XamForms.Test"
+    x:TypeArguments="vm:ActivatingViewModel2">
+
+    <!--
+        The overall app visual hierarchy is defined here, along with navigation.
+
+        https://docs.microsoft.com/xamarin/xamarin-forms/app-fundamentals/shell/
+    -->
+    <Shell.Resources>
+        <ResourceDictionary>
+            <Style x:Key="BaseStyle" TargetType="Element">
+                <Setter Property="Shell.BackgroundColor" Value="{StaticResource Primary}" />
+                <Setter Property="Shell.ForegroundColor" Value="White" />
+                <Setter Property="Shell.TitleColor" Value="White" />
+                <Setter Property="Shell.DisabledColor" Value="#B4FFFFFF" />
+                <Setter Property="Shell.UnselectedColor" Value="#95FFFFFF" />
+                <Setter Property="Shell.TabBarBackgroundColor" Value="{StaticResource Primary}" />
+                <Setter Property="Shell.TabBarForegroundColor" Value="White" />
+                <Setter Property="Shell.TabBarUnselectedColor" Value="#95FFFFFF" />
+                <Setter Property="Shell.TabBarTitleColor" Value="White" />
+            </Style>
+            <Style BasedOn="{StaticResource BaseStyle}" TargetType="TabBar" />
+            <Style BasedOn="{StaticResource BaseStyle}" TargetType="FlyoutItem" />
+        </ResourceDictionary>
+    </Shell.Resources>
+
+    <rxui:ShellViewModel Title="Shell" x:TypeArguments="vm:ShellViewModel" />
+    <rxui:ShellViewModel Title="Content" x:TypeArguments="vm:ContentPageViewModel" />
+    <rxui:ShellViewModel Title="Tabbed" x:TypeArguments="vm:TabbedPageViewModel" />
+    <rxui:ShellViewModel Title="Carousel" x:TypeArguments="vm:CarouselPageViewModel" />
+    <rxui:ShellViewModel Title="FlyOut" x:TypeArguments="vm:FlyOutPageViewModel" />
+</rxui:ReactiveShell>
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShell.xaml.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShell.xaml.cs
new file mode 100644
index 0000000000..36899fd9cb
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShell.xaml.cs
@@ -0,0 +1,35 @@
+// Copyright (c) 2021 .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 System.Reactive.Disposables;
+
+namespace ReactiveUI.XamForms.Tests.Activation
+{
+    /// <summary>
+    /// App Shell.
+    /// </summary>
+    /// <seealso cref="Xamarin.Forms.Shell" />
+    public partial class AppShell
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="AppShell"/> class.
+        /// </summary>
+        public AppShell()
+        {
+            InitializeComponent();
+            ViewModel = new();
+            this.WhenActivated(d =>
+            {
+                IsActiveCount++;
+                d(Disposable.Create(() => IsActiveCount--));
+            });
+        }
+
+        /// <summary>
+        /// Gets or sets the active count.
+        /// </summary>
+        public int IsActiveCount { get; set; }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ApplicationMock.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ApplicationMock.cs
new file mode 100644
index 0000000000..a0a8dd1631
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ApplicationMock.cs
@@ -0,0 +1,23 @@
+// Copyright (c) 2021 .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 Xamarin.Forms;
+
+namespace ReactiveUI.Tests
+{
+    /// <summary>
+    /// Application Mock.
+    /// </summary>
+    /// <seealso cref="Application" />
+    public class ApplicationMock : Application
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ApplicationMock"/> class.
+        /// </summary>
+        public ApplicationMock()
+        {
+        }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/CarouselPageView.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/CarouselPageView.cs
new file mode 100644
index 0000000000..32f53cb7bf
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/CarouselPageView.cs
@@ -0,0 +1,30 @@
+// Copyright (c) 2021 .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 System.Reactive.Disposables;
+
+namespace ReactiveUI.XamForms.Tests.Activation
+{
+    /// <summary>
+    /// Carousel Page View.
+    /// </summary>
+    public class CarouselPageView : ReactiveCarouselPage<CarouselPageViewModel>
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="CarouselPageView"/> class.
+        /// </summary>
+        public CarouselPageView() =>
+            this.WhenActivated(d =>
+            {
+                IsActiveCount++;
+                d(Disposable.Create(() => IsActiveCount--));
+            });
+
+        /// <summary>
+        /// Gets or sets the active count.
+        /// </summary>
+        public int IsActiveCount { get; set; }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/CarouselPageViewModel.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/CarouselPageViewModel.cs
new file mode 100644
index 0000000000..1efdec19c9
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/CarouselPageViewModel.cs
@@ -0,0 +1,39 @@
+// Copyright (c) 2021 .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 System.Reactive.Disposables;
+
+namespace ReactiveUI.XamForms.Tests.Activation
+{
+    /// <summary>
+    /// Simulates a activating view model.
+    /// </summary>
+    public class CarouselPageViewModel : ReactiveObject, IActivatableViewModel
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="CarouselPageViewModel"/> class.
+        /// </summary>
+        public CarouselPageViewModel()
+        {
+            Activator = new ViewModelActivator();
+
+            this.WhenActivated(d =>
+            {
+                IsActiveCount++;
+                d(Disposable.Create(() => IsActiveCount--));
+            });
+        }
+
+        /// <summary>
+        /// Gets or sets the Activator which will be used by the View when Activation/Deactivation occurs.
+        /// </summary>
+        public ViewModelActivator Activator { get; protected set; }
+
+        /// <summary>
+        /// Gets or sets the active count.
+        /// </summary>
+        public int IsActiveCount { get; protected set; }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ContentPageView.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ContentPageView.cs
new file mode 100644
index 0000000000..a91ad6492a
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ContentPageView.cs
@@ -0,0 +1,31 @@
+// Copyright (c) 2021 .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 System.Reactive.Disposables;
+using ReactiveUI.Tests;
+
+namespace ReactiveUI.XamForms.Tests.Activation
+{
+    /// <summary>
+    /// Content Page View.
+    /// </summary>
+    public class ContentPageView : ReactiveContentPage<ContentPageViewModel>
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ContentPageView"/> class.
+        /// </summary>
+        public ContentPageView() =>
+            this.WhenActivated(d =>
+            {
+                IsActiveCount++;
+                d(Disposable.Create(() => IsActiveCount--));
+            });
+
+        /// <summary>
+        /// Gets or sets the active count.
+        /// </summary>
+        public int IsActiveCount { get; set; }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ContentPageViewModel.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ContentPageViewModel.cs
new file mode 100644
index 0000000000..63ba7a89ff
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ContentPageViewModel.cs
@@ -0,0 +1,41 @@
+// Copyright (c) 2021 .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 System.Reactive.Disposables;
+
+namespace ReactiveUI.XamForms.Tests.Activation
+{
+    /// <summary>
+    /// ContentPageViewModel.
+    /// </summary>
+    /// <seealso cref="ReactiveUI.ReactiveObject" />
+    /// <seealso cref="ReactiveUI.IActivatableViewModel" />
+    public class ContentPageViewModel : ReactiveObject, IActivatableViewModel
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ContentPageViewModel"/> class.
+        /// </summary>
+        public ContentPageViewModel()
+        {
+            Activator = new ViewModelActivator();
+
+            this.WhenActivated(d =>
+            {
+                IsActiveCount++;
+                d(Disposable.Create(() => IsActiveCount--));
+            });
+        }
+
+        /// <summary>
+        /// Gets or sets the Activator which will be used by the View when Activation/Deactivation occurs.
+        /// </summary>
+        public ViewModelActivator Activator { get; protected set; }
+
+        /// <summary>
+        /// Gets or sets the active count.
+        /// </summary>
+        public int IsActiveCount { get; protected set; }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyOutPageViewModel.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyOutPageViewModel.cs
new file mode 100644
index 0000000000..adb118cbfd
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyOutPageViewModel.cs
@@ -0,0 +1,41 @@
+// Copyright (c) 2021 .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 System.Reactive.Disposables;
+
+namespace ReactiveUI.XamForms.Tests.Activation
+{
+    /// <summary>
+    /// FlyOutPageViewModel.
+    /// </summary>
+    /// <seealso cref="ReactiveUI.ReactiveObject" />
+    /// <seealso cref="ReactiveUI.IActivatableViewModel" />
+    public class FlyOutPageViewModel : ReactiveObject, IActivatableViewModel
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="FlyOutPageViewModel"/> class.
+        /// </summary>
+        public FlyOutPageViewModel()
+        {
+            Activator = new ViewModelActivator();
+
+            this.WhenActivated(d =>
+            {
+                IsActiveCount++;
+                d(Disposable.Create(() => IsActiveCount--));
+            });
+        }
+
+        /// <summary>
+        /// Gets or sets the Activator which will be used by the View when Activation/Deactivation occurs.
+        /// </summary>
+        public ViewModelActivator Activator { get; protected set; }
+
+        /// <summary>
+        /// Gets or sets the active count.
+        /// </summary>
+        public int IsActiveCount { get; protected set; }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageView.xaml b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageView.xaml
new file mode 100644
index 0000000000..1440ae0a35
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageView.xaml
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<rxui:ReactiveFlyoutPage
+    x:Class="ReactiveUI.XamForms.Tests.Activation.Mocks.FlyoutPageView"
+    xmlns="http://xamarin.com/schemas/2014/forms"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    xmlns:pages="clr-namespace:ReactiveUI.XamForms.Tests.Activation.Mocks"
+    xmlns:rxui="clr-namespace:ReactiveUI.XamForms;assembly=ReactiveUI.XamForms"
+    xmlns:vm="clr-namespace:ReactiveUI.XamForms.Tests.Activation"
+    x:TypeArguments="vm:FlyOutPageViewModel">
+    <FlyoutPage.Flyout>
+        <pages:FlyoutPageViewFlyout x:Name="FlyoutPage" />
+    </FlyoutPage.Flyout>
+    <FlyoutPage.Detail>
+        <NavigationPage>
+            <x:Arguments>
+                <pages:FlyoutPageViewDetail />
+            </x:Arguments>
+        </NavigationPage>
+    </FlyoutPage.Detail>
+</rxui:ReactiveFlyoutPage>
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageView.xaml.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageView.xaml.cs
new file mode 100644
index 0000000000..74143c459f
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageView.xaml.cs
@@ -0,0 +1,57 @@
+// Copyright (c) 2021 .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 System;
+using System.Reactive.Disposables;
+using Xamarin.Forms;
+using Xamarin.Forms.Xaml;
+
+namespace ReactiveUI.XamForms.Tests.Activation.Mocks
+{
+    /// <summary>
+    /// Flyout Page View.
+    /// </summary>
+    [XamlCompilation(XamlCompilationOptions.Compile)]
+    public partial class FlyoutPageView
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="FlyoutPageView"/> class.
+        /// </summary>
+        public FlyoutPageView()
+        {
+            InitializeComponent();
+
+            this.WhenActivated(d =>
+            {
+                IsActiveCount++;
+                d(Disposable.Create(() => IsActiveCount--));
+            });
+
+            FlyoutPage.ListView.ItemSelected += ListView_ItemSelected;
+        }
+
+        /// <summary>
+        /// Gets or sets the active count.
+        /// </summary>
+        public int IsActiveCount { get; set; }
+
+        private void ListView_ItemSelected(object? sender, SelectedItemChangedEventArgs e)
+        {
+            var item = e.SelectedItem as FlyoutPageViewFlyoutMenuItem;
+            if (item == null)
+            {
+                return;
+            }
+
+            var page = (Page?)Activator.CreateInstance(item.TargetType);
+            page!.Title = item.Title;
+
+            Detail = new NavigationPage(page);
+            IsPresented = false;
+
+            FlyoutPage.ListView.SelectedItem = null;
+        }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewDetail.xaml b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewDetail.xaml
new file mode 100644
index 0000000000..33b7bacae3
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewDetail.xaml
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage
+    x:Class="ReactiveUI.XamForms.Tests.Activation.Mocks.FlyoutPageViewDetail"
+    xmlns="http://xamarin.com/schemas/2014/forms"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    Title="Detail">
+    <StackLayout Padding="10">
+        <Label Text="This is a detail page. To get the 'triple' line icon on each platform add a icon to each platform and update the 'Flyout' page with an Icon that references it." />
+    </StackLayout>
+</ContentPage>
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewDetail.xaml.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewDetail.xaml.cs
new file mode 100644
index 0000000000..a434f978b4
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewDetail.xaml.cs
@@ -0,0 +1,26 @@
+// Copyright (c) 2021 .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 Xamarin.Forms;
+using Xamarin.Forms.Xaml;
+
+namespace ReactiveUI.XamForms.Tests.Activation.Mocks
+{
+    /// <summary>
+    /// FlyoutPageView Detail.
+    /// </summary>
+    /// <seealso cref="Xamarin.Forms.ContentPage" />
+    [XamlCompilation(XamlCompilationOptions.Compile)]
+    public partial class FlyoutPageViewDetail : ContentPage
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="FlyoutPageViewDetail"/> class.
+        /// </summary>
+        public FlyoutPageViewDetail()
+        {
+            InitializeComponent();
+        }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewFlyout.xaml b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewFlyout.xaml
new file mode 100644
index 0000000000..f20eb06d1f
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewFlyout.xaml
@@ -0,0 +1,48 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage
+    x:Class="ReactiveUI.XamForms.Tests.Activation.Mocks.FlyoutPageViewFlyout"
+    xmlns="http://xamarin.com/schemas/2014/forms"
+    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+    Title="Flyout">
+    <StackLayout>
+        <ListView
+            x:Name="MenuItemsListView"
+            HasUnevenRows="true"
+            ItemsSource="{Binding MenuItems}"
+            SeparatorVisibility="None">
+            <ListView.Header>
+                <Grid BackgroundColor="#03A9F4">
+                    <Grid.ColumnDefinitions>
+                        <ColumnDefinition Width="10" />
+                        <ColumnDefinition Width="*" />
+                        <ColumnDefinition Width="10" />
+                    </Grid.ColumnDefinitions>
+                    <Grid.RowDefinitions>
+                        <RowDefinition Height="30" />
+                        <RowDefinition Height="80" />
+                        <RowDefinition Height="Auto" />
+                        <RowDefinition Height="10" />
+                    </Grid.RowDefinitions>
+                    <Label
+                        Grid.Row="2"
+                        Grid.Column="1"
+                        Style="{DynamicResource SubtitleStyle}"
+                        Text="AppName" />
+                </Grid>
+            </ListView.Header>
+            <ListView.ItemTemplate>
+                <DataTemplate>
+                    <ViewCell>
+                        <StackLayout Padding="15,10" HorizontalOptions="FillAndExpand">
+                            <Label
+                                FontSize="24"
+                                Text="{Binding Title}"
+                                VerticalOptions="FillAndExpand"
+                                VerticalTextAlignment="Center" />
+                        </StackLayout>
+                    </ViewCell>
+                </DataTemplate>
+            </ListView.ItemTemplate>
+        </ListView>
+    </StackLayout>
+</ContentPage>
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewFlyout.xaml.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewFlyout.xaml.cs
new file mode 100644
index 0000000000..16e0d1581c
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewFlyout.xaml.cs
@@ -0,0 +1,81 @@
+// Copyright (c) 2021 .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 System.Collections.ObjectModel;
+using System.ComponentModel;
+using System.Runtime.CompilerServices;
+using Xamarin.Forms;
+using Xamarin.Forms.Xaml;
+
+namespace ReactiveUI.XamForms.Tests.Activation.Mocks
+{
+    /// <summary>
+    /// Flyout Page View Flyout.
+    /// </summary>
+    /// <seealso cref="Xamarin.Forms.ContentPage" />
+    [XamlCompilation(XamlCompilationOptions.Compile)]
+    public partial class FlyoutPageViewFlyout : ContentPage
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="FlyoutPageViewFlyout"/> class.
+        /// </summary>
+        public FlyoutPageViewFlyout()
+        {
+            InitializeComponent();
+
+            BindingContext = new FlyoutPageView1FlyoutViewModel();
+            ListView = MenuItemsListView;
+        }
+
+        /// <summary>
+        /// Gets the ListView.
+        /// </summary>
+        /// <value>
+        /// The ListView.
+        /// </value>
+        public ListView ListView { get; }
+
+        private class FlyoutPageView1FlyoutViewModel : INotifyPropertyChanged
+        {
+            /// <summary>
+            /// Initializes a new instance of the <see cref="FlyoutPageView1FlyoutViewModel"/> class.
+            /// </summary>
+            public FlyoutPageView1FlyoutViewModel()
+            {
+                MenuItems = new ObservableCollection<FlyoutPageViewFlyoutMenuItem>(new[]
+                {
+                    new FlyoutPageViewFlyoutMenuItem { Id = 0, Title = "Page 1" },
+                    new FlyoutPageViewFlyoutMenuItem { Id = 1, Title = "Page 2" },
+                    new FlyoutPageViewFlyoutMenuItem { Id = 2, Title = "Page 3" },
+                    new FlyoutPageViewFlyoutMenuItem { Id = 3, Title = "Page 4" },
+                    new FlyoutPageViewFlyoutMenuItem { Id = 4, Title = "Page 5" },
+                });
+            }
+
+            /// <summary>
+            /// Occurs when a property value changes.
+            /// </summary>
+            public event PropertyChangedEventHandler? PropertyChanged;
+
+            /// <summary>
+            /// Gets or sets the menu items.
+            /// </summary>
+            /// <value>
+            /// The menu items.
+            /// </value>
+            public ObservableCollection<FlyoutPageViewFlyoutMenuItem> MenuItems { get; set; }
+
+            private void OnPropertyChanged([CallerMemberName] string propertyName = "")
+            {
+                if (PropertyChanged == null)
+                {
+                    return;
+                }
+
+                PropertyChanged.Invoke(this, new PropertyChangedEventArgs(propertyName));
+            }
+        }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewFlyoutMenuItem.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewFlyoutMenuItem.cs
new file mode 100644
index 0000000000..af3b879d3e
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/FlyoutPageViewFlyoutMenuItem.cs
@@ -0,0 +1,47 @@
+// Copyright (c) 2021 .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 System;
+
+namespace ReactiveUI.XamForms.Tests.Activation.Mocks
+{
+    /// <summary>
+    /// FlyoutPageViewFlyoutMenuItem.
+    /// </summary>
+    public class FlyoutPageViewFlyoutMenuItem
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="FlyoutPageViewFlyoutMenuItem"/> class.
+        /// </summary>
+        public FlyoutPageViewFlyoutMenuItem()
+        {
+            TargetType = typeof(FlyoutPageViewFlyoutMenuItem);
+        }
+
+        /// <summary>
+        /// Gets or sets the identifier.
+        /// </summary>
+        /// <value>
+        /// The identifier.
+        /// </value>
+        public int Id { get; set; }
+
+        /// <summary>
+        /// Gets or sets the title.
+        /// </summary>
+        /// <value>
+        /// The title.
+        /// </value>
+        public string? Title { get; set; }
+
+        /// <summary>
+        /// Gets or sets the type of the target.
+        /// </summary>
+        /// <value>
+        /// The type of the target.
+        /// </value>
+        public Type TargetType { get; set; }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/MockForms.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/MockForms.cs
new file mode 100644
index 0000000000..264ba2f754
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/MockForms.cs
@@ -0,0 +1,241 @@
+// Copyright (c) 2021 .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 System;
+using System.Collections.Generic;
+using System.IO;
+using System.Reflection;
+using System.Security.Cryptography;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Xamarin.Forms;
+using Xamarin.Forms.Internals;
+
+namespace ReactiveUI.Tests
+{
+    /// <summary>
+    /// Mock Forms.
+    /// </summary>
+    public static class MockForms
+    {
+        /// <summary>
+        /// Initializes this instance.
+        /// </summary>
+        public static void Init()
+        {
+            Device.Info = new MockDeviceInfo();
+            Device.PlatformServices = new MockPlatformServices();
+
+            DependencyService.Register<MockResourcesProvider>();
+            DependencyService.Register<MockDeserializer>();
+        }
+
+        internal class MockPlatformServices : IPlatformServices
+        {
+            private Action<Action>? _invokeOnMainThread;
+            private Action<Uri>? _openUriAction;
+            private Func<Uri, CancellationToken, Task<Stream>>? _getStreamAsync;
+
+            public MockPlatformServices(Action<Action>? invokeOnMainThread = null, Action<Uri>? openUriAction = null, Func<Uri, CancellationToken, Task<Stream>>? getStreamAsync = null)
+            {
+                _invokeOnMainThread = invokeOnMainThread;
+                _openUriAction = openUriAction;
+                _getStreamAsync = getStreamAsync;
+            }
+
+            public bool IsInvokeRequired
+            {
+                get { return false; }
+            }
+
+            public string? RuntimePlatform { get; set; }
+
+            public OSAppTheme RequestedTheme => OSAppTheme.Dark;
+
+            public static int Hex(int v) => v < 10 ? '0' + v : 'a' + v - 10;
+
+            public void OpenUriAction(Uri uri)
+            {
+                if (_openUriAction != null)
+                {
+                    _openUriAction(uri);
+                }
+                else
+                {
+                    throw new NotImplementedException();
+                }
+            }
+
+            public void BeginInvokeOnMainThread(Action action)
+            {
+                if (_invokeOnMainThread == null)
+                {
+                    action();
+                }
+                else
+                {
+                    _invokeOnMainThread(action);
+                }
+            }
+
+            public string GetMD5Hash(string input)
+            {
+                // Step 1, calculate MD5 hash from input
+                var md5 = MD5.Create();
+                var inputBytes = Encoding.ASCII.GetBytes(input);
+                var hashBytes = md5.ComputeHash(inputBytes);
+
+                // Step 2, convert byte array to hex string
+                var sb = new StringBuilder();
+                for (var i = 0; i < hashBytes.Length; i++)
+                {
+                    sb.Append(hashBytes[i].ToString("X2"));
+                }
+
+                return sb.ToString();
+            }
+
+            public double GetNamedSize(NamedSize size, Type targetElement, bool useOldSizes)
+            {
+                switch (size)
+                {
+                    case NamedSize.Default:
+                        return 10;
+
+                    case NamedSize.Micro:
+                        return 4;
+
+                    case NamedSize.Small:
+                        return 8;
+
+                    case NamedSize.Medium:
+                        return 12;
+
+                    case NamedSize.Large:
+                        return 16;
+
+                    default:
+                        throw new ArgumentOutOfRangeException(nameof(size));
+                }
+            }
+
+            public Ticker CreateTicker() => new MockTicker();
+
+            public void StartTimer(TimeSpan interval, Func<bool> callback)
+            {
+                Timer? timer = null;
+                TimerCallback onTimeout = o => BeginInvokeOnMainThread(() =>
+                {
+                    if (callback())
+                    {
+                        return;
+                    }
+
+                    timer?.Dispose();
+                });
+                timer = new Timer(onTimeout, null, interval, interval);
+            }
+
+            public Task<Stream> GetStreamAsync(Uri uri, CancellationToken cancellationToken)
+            {
+                if (_getStreamAsync == null)
+                {
+                    throw new NotImplementedException();
+                }
+
+                return _getStreamAsync(uri, cancellationToken);
+            }
+
+            public Assembly[] GetAssemblies() => new Assembly[0];
+
+            public IIsolatedStorageFile GetUserStoreForApplication()
+            {
+                throw new NotImplementedException();
+            }
+
+            public string GetHash(string input) => throw new NotImplementedException();
+
+            public Color GetNamedColor(string name) => Color.DeepSkyBlue;
+
+            public void QuitApplication()
+            {
+            }
+
+            public SizeRequest GetNativeSize(VisualElement view, double widthConstraint, double heightConstraint) => throw new NotImplementedException();
+        }
+
+        internal class MockDeserializer : IDeserializer
+        {
+            public Task<IDictionary<string, object>> DeserializePropertiesAsync() =>
+                Task.FromResult<IDictionary<string, object>>(new Dictionary<string, object>());
+
+            public Task SerializePropertiesAsync(IDictionary<string, object> properties) =>
+                Task.FromResult(false);
+        }
+
+        internal class MockResourcesProvider : ISystemResourcesProvider
+        {
+            public IResourceDictionary GetSystemResources()
+            {
+                var dictionary = new ResourceDictionary();
+                Style style;
+                style = new Style(typeof(Label));
+                dictionary[Device.Styles.BodyStyleKey] = style;
+
+                style = new Style(typeof(Label));
+                style.Setters.Add(Label.FontSizeProperty, 50);
+                dictionary[Device.Styles.TitleStyleKey] = style;
+
+                style = new Style(typeof(Label));
+                style.Setters.Add(Label.FontSizeProperty, 40);
+                dictionary[Device.Styles.SubtitleStyleKey] = style;
+
+                style = new Style(typeof(Label));
+                style.Setters.Add(Label.FontSizeProperty, 30);
+                dictionary[Device.Styles.CaptionStyleKey] = style;
+
+                style = new Style(typeof(Label));
+                style.Setters.Add(Label.FontSizeProperty, 20);
+                dictionary[Device.Styles.ListItemTextStyleKey] = style;
+
+                style = new Style(typeof(Label));
+                style.Setters.Add(Label.FontSizeProperty, 10);
+                dictionary[Device.Styles.ListItemDetailTextStyleKey] = style;
+
+                return dictionary;
+            }
+        }
+
+        internal class MockTicker : Ticker
+        {
+            private bool _enabled;
+
+            protected override void EnableTimer()
+            {
+                _enabled = true;
+
+                while (_enabled)
+                {
+                    SendSignals(16);
+                }
+            }
+
+            protected override void DisableTimer()
+            {
+                _enabled = false;
+            }
+        }
+
+        internal class MockDeviceInfo : DeviceInfo
+        {
+            public override Size PixelScreenSize => throw new NotImplementedException();
+
+            public override Size ScaledScreenSize => throw new NotImplementedException();
+
+            public override double ScalingFactor => throw new NotImplementedException();
+        }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ShellView.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ShellView.cs
new file mode 100644
index 0000000000..d39d530fbc
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ShellView.cs
@@ -0,0 +1,34 @@
+// Copyright (c) 2021 .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 System.Reactive.Disposables;
+using ReactiveUI.Tests;
+
+namespace ReactiveUI.XamForms.Tests.Activation
+{
+    /// <summary>
+    /// Shell View.
+    /// </summary>
+    public class ShellView : ReactiveShell<ShellViewModel>
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ShellView"/> class.
+        /// </summary>
+        public ShellView()
+        {
+            ViewModel = new();
+            this.WhenActivated(d =>
+            {
+                IsActiveCount++;
+                d(Disposable.Create(() => IsActiveCount--));
+            });
+        }
+
+        /// <summary>
+        /// Gets or sets the active count.
+        /// </summary>
+        public int IsActiveCount { get; set; }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ShellViewModel.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ShellViewModel.cs
new file mode 100644
index 0000000000..5778865dd3
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ShellViewModel.cs
@@ -0,0 +1,41 @@
+// Copyright (c) 2021 .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 System.Reactive.Disposables;
+
+namespace ReactiveUI.XamForms.Tests.Activation
+{
+    /// <summary>
+    /// ShellViewModel.
+    /// </summary>
+    /// <seealso cref="ReactiveUI.ReactiveObject" />
+    /// <seealso cref="ReactiveUI.IActivatableViewModel" />
+    public class ShellViewModel : ReactiveObject, IActivatableViewModel
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ShellViewModel"/> class.
+        /// </summary>
+        public ShellViewModel()
+        {
+            Activator = new ViewModelActivator();
+
+            this.WhenActivated(d =>
+            {
+                IsActiveCount++;
+                d(Disposable.Create(() => IsActiveCount--));
+            });
+        }
+
+        /// <summary>
+        /// Gets or sets the Activator which will be used by the View when Activation/Deactivation occurs.
+        /// </summary>
+        public ViewModelActivator Activator { get; protected set; }
+
+        /// <summary>
+        /// Gets or sets the active count.
+        /// </summary>
+        public int IsActiveCount { get; protected set; }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/TabbedPageView.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/TabbedPageView.cs
new file mode 100644
index 0000000000..05bd5fc0d4
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/TabbedPageView.cs
@@ -0,0 +1,30 @@
+// Copyright (c) 2021 .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 System.Reactive.Disposables;
+
+namespace ReactiveUI.XamForms.Tests.Activation
+{
+    /// <summary>
+    /// Tabbed Page View.
+    /// </summary>
+    public class TabbedPageView : ReactiveTabbedPage<TabbedPageViewModel>
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="TabbedPageView"/> class.
+        /// </summary>
+        public TabbedPageView() =>
+            this.WhenActivated(d =>
+            {
+                IsActiveCount++;
+                d(Disposable.Create(() => IsActiveCount--));
+            });
+
+        /// <summary>
+        /// Gets or sets the active count.
+        /// </summary>
+        public int IsActiveCount { get; set; }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/TabbedPageViewModel.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/TabbedPageViewModel.cs
new file mode 100644
index 0000000000..88c5b15441
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/TabbedPageViewModel.cs
@@ -0,0 +1,41 @@
+// Copyright (c) 2021 .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 System.Reactive.Disposables;
+
+namespace ReactiveUI.XamForms.Tests.Activation
+{
+    /// <summary>
+    /// TabbedPageViewModel.
+    /// </summary>
+    /// <seealso cref="ReactiveUI.ReactiveObject" />
+    /// <seealso cref="ReactiveUI.IActivatableViewModel" />
+    public class TabbedPageViewModel : ReactiveObject, IActivatableViewModel
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="TabbedPageViewModel"/> class.
+        /// </summary>
+        public TabbedPageViewModel()
+        {
+            Activator = new ViewModelActivator();
+
+            this.WhenActivated(d =>
+            {
+                IsActiveCount++;
+                d(Disposable.Create(() => IsActiveCount--));
+            });
+        }
+
+        /// <summary>
+        /// Gets or sets the Activator which will be used by the View when Activation/Deactivation occurs.
+        /// </summary>
+        public ViewModelActivator Activator { get; protected set; }
+
+        /// <summary>
+        /// Gets or sets the active count.
+        /// </summary>
+        public int IsActiveCount { get; protected set; }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/ReactiveUI.XamForms.Tests.csproj b/src/ReactiveUI.XamForms.Tests/ReactiveUI.XamForms.Tests.csproj
index 4a0985c33c..d6e6fd28ed 100644
--- a/src/ReactiveUI.XamForms.Tests/ReactiveUI.XamForms.Tests.csproj
+++ b/src/ReactiveUI.XamForms.Tests/ReactiveUI.XamForms.Tests.csproj
@@ -9,4 +9,34 @@
     <ProjectReference Include="..\ReactiveUI.XamForms\ReactiveUI.XamForms.csproj" />
   </ItemGroup>
 
+  <ItemGroup>
+    <Compile Update="Activation\Mocks\FlyoutPageView.xaml.cs">
+      <DependentUpon>FlyoutPageView.xaml</DependentUpon>
+    </Compile>
+    <Compile Update="Activation\Mocks\FlyoutPageViewFlyout.xaml.cs">
+      <DependentUpon>FlyoutPageViewFlyout.xaml</DependentUpon>
+    </Compile>
+    <Compile Update="Activation\Mocks\FlyoutPageViewDetail.xaml.cs">
+      <DependentUpon>FlyoutPageViewDetail.xaml</DependentUpon>
+    </Compile>
+  </ItemGroup>
+
+  <ItemGroup>
+    <EmbeddedResource Update="Activation\Mocks\App.xaml">
+      <Generator>MSBuild:Compile</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="Activation\Mocks\AppShell.xaml">
+      <Generator>MSBuild:Compile</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="Activation\Mocks\FlyoutPageView.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="Activation\Mocks\FlyoutPageViewDetail.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+    <EmbeddedResource Update="Activation\Mocks\FlyoutPageViewFlyout.xaml">
+      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
+    </EmbeddedResource>
+  </ItemGroup>
+
 </Project>
diff --git a/src/ReactiveUI.XamForms/ActivationForViewFetcher.cs b/src/ReactiveUI.XamForms/ActivationForViewFetcher.cs
index fc3dc351b8..e691e6cb46 100644
--- a/src/ReactiveUI.XamForms/ActivationForViewFetcher.cs
+++ b/src/ReactiveUI.XamForms/ActivationForViewFetcher.cs
@@ -19,6 +19,7 @@ public class ActivationForViewFetcher : IActivationForViewFetcher
     {
         /// <inheritdoc/>
         public int GetAffinityForView(Type view) =>
+            typeof(Shell).GetTypeInfo().IsAssignableFrom(view.GetTypeInfo()) ||
             typeof(Page).GetTypeInfo().IsAssignableFrom(view.GetTypeInfo()) ||
             typeof(View).GetTypeInfo().IsAssignableFrom(view.GetTypeInfo()) ||
             typeof(Cell).GetTypeInfo().IsAssignableFrom(view.GetTypeInfo())
@@ -29,6 +30,7 @@ public IObservable<bool> GetActivationForView(IActivatableView view)
         {
             var activation =
                 GetActivationFor(view as ICanActivate) ??
+                GetActivationFor(view as Shell) ??
                 GetActivationFor(view as Page) ??
                 GetActivationFor(view as View) ??
                 GetActivationFor(view as Cell) ??
@@ -116,5 +118,29 @@ public IObservable<bool> GetActivationForView(IActivatableView view)
 
             return appearing.Merge(disappearing);
         }
+
+        private static IObservable<bool>? GetActivationFor(Shell? shell)
+        {
+            if (shell is null)
+            {
+                return null;
+            }
+
+            var appearing = shell.WhenAnyValue(x => x.Navigation.NavigationStack.Count)
+                .Where(x => x > 0)
+                .DistinctUntilChanged()
+                .Select(_ => true);
+
+            var disappearing = Observable.FromEvent<EventHandler, bool>(
+                    eventHandler =>
+                    {
+                        void Handler(object? sender, EventArgs e) => eventHandler(false);
+                        return Handler;
+                    },
+                    x => shell.Disappearing += x,
+                    x => shell.Disappearing -= x);
+
+            return appearing.Merge(disappearing);
+        }
     }
 }
diff --git a/src/ReactiveUI.XamForms/ReactiveFlyoutPage.cs b/src/ReactiveUI.XamForms/ReactiveFlyoutPage.cs
new file mode 100644
index 0000000000..78bb839b53
--- /dev/null
+++ b/src/ReactiveUI.XamForms/ReactiveFlyoutPage.cs
@@ -0,0 +1,55 @@
+// Copyright (c) 2021 .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 Xamarin.Forms;
+
+namespace ReactiveUI.XamForms
+{
+    /// <summary>
+    /// Reactive Flyout Page.
+    /// </summary>
+    /// <typeparam name="TViewModel">The type of the view model.</typeparam>
+    /// <seealso cref="Xamarin.Forms.FlyoutPage" />
+    /// <seealso cref="ReactiveUI.IViewFor{TViewModel}" />
+    public class ReactiveFlyoutPage<TViewModel> : FlyoutPage, IViewFor<TViewModel>
+        where TViewModel : class
+    {
+        /// <summary>
+        /// The view model bindable property.
+        /// </summary>
+        public static readonly BindableProperty ViewModelProperty = BindableProperty.Create(
+            nameof(ViewModel),
+            typeof(TViewModel),
+            typeof(ReactiveFlyoutPage<TViewModel>),
+            default(TViewModel),
+            BindingMode.OneWay,
+            propertyChanged: OnViewModelChanged);
+
+        /// <summary>
+        /// Gets or sets the ViewModel to display.
+        /// </summary>
+        public TViewModel? ViewModel
+        {
+            get => (TViewModel)GetValue(ViewModelProperty);
+            set => SetValue(ViewModelProperty, value);
+        }
+
+        /// <inheritdoc/>
+        object? IViewFor.ViewModel
+        {
+            get => ViewModel;
+            set => ViewModel = (TViewModel?)value;
+        }
+
+        /// <inheritdoc/>
+        protected override void OnBindingContextChanged()
+        {
+            base.OnBindingContextChanged();
+            ViewModel = BindingContext as TViewModel;
+        }
+
+        private static void OnViewModelChanged(BindableObject bindableObject, object oldValue, object newValue) => bindableObject.BindingContext = newValue;
+    }
+}
diff --git a/src/ReactiveUI.XamForms/ReactiveMasterDetailPage.cs b/src/ReactiveUI.XamForms/ReactiveMasterDetailPage.cs
index 4baa4a5e03..a0880143cd 100644
--- a/src/ReactiveUI.XamForms/ReactiveMasterDetailPage.cs
+++ b/src/ReactiveUI.XamForms/ReactiveMasterDetailPage.cs
@@ -3,6 +3,7 @@
 // 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 System;
 using Xamarin.Forms;
 
 namespace ReactiveUI.XamForms
@@ -13,6 +14,7 @@ namespace ReactiveUI.XamForms
     /// <typeparam name="TViewModel">The type of the view model.</typeparam>
     /// <seealso cref="Xamarin.Forms.MasterDetailPage" />
     /// <seealso cref="ReactiveUI.IViewFor{TViewModel}" />
+    [Obsolete("ReactiveMasterDetailPage is obsolete as of version 5.0.0. Please use FlyoutPage instead.")]
     public class ReactiveMasterDetailPage<TViewModel> : MasterDetailPage, IViewFor<TViewModel>
         where TViewModel : class
     {
diff --git a/src/ReactiveUI.XamForms/ReactiveShell.cs b/src/ReactiveUI.XamForms/ReactiveShell.cs
new file mode 100644
index 0000000000..a78d8c48fe
--- /dev/null
+++ b/src/ReactiveUI.XamForms/ReactiveShell.cs
@@ -0,0 +1,55 @@
+// Copyright (c) 2021 .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 Xamarin.Forms;
+
+namespace ReactiveUI.XamForms
+{
+    /// <summary>
+    /// Reactive Shell.
+    /// </summary>
+    /// <typeparam name="TViewModel">The type of the view model.</typeparam>
+    /// <seealso cref="Xamarin.Forms.Shell" />
+    /// <seealso cref="ReactiveUI.IViewFor{TViewModel}" />
+    public class ReactiveShell<TViewModel> : Shell, IViewFor<TViewModel>
+        where TViewModel : class
+    {
+        /// <summary>
+        /// The view model bindable property.
+        /// </summary>
+        public static readonly BindableProperty ViewModelProperty = BindableProperty.Create(
+            nameof(ViewModel),
+            typeof(TViewModel),
+            typeof(ReactiveShell<TViewModel>),
+            default(TViewModel),
+            BindingMode.OneWay,
+            propertyChanged: OnViewModelChanged);
+
+        /// <summary>
+        /// Gets or sets the ViewModel to display.
+        /// </summary>
+        public TViewModel? ViewModel
+        {
+            get => (TViewModel)GetValue(ViewModelProperty);
+            set => SetValue(ViewModelProperty, value);
+        }
+
+        /// <inheritdoc/>
+        object? IViewFor.ViewModel
+        {
+            get => ViewModel;
+            set => ViewModel = (TViewModel?)value;
+        }
+
+        /// <inheritdoc/>
+        protected override void OnBindingContextChanged()
+        {
+            base.OnBindingContextChanged();
+            ViewModel = BindingContext as TViewModel;
+        }
+
+        private static void OnViewModelChanged(BindableObject bindableObject, object oldValue, object newValue) => bindableObject.BindingContext = newValue;
+    }
+}
diff --git a/src/ReactiveUI.XamForms/ShellViewModel.cs b/src/ReactiveUI.XamForms/ShellViewModel.cs
new file mode 100644
index 0000000000..99a295545a
--- /dev/null
+++ b/src/ReactiveUI.XamForms/ShellViewModel.cs
@@ -0,0 +1,89 @@
+// Copyright (c) 2021 .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 Splat;
+using Xamarin.Forms;
+
+namespace ReactiveUI.XamForms
+{
+    /// <summary>
+    /// ShellViewModel.
+    /// </summary>
+    /// <typeparam name="TViewModel">The type of the view model.</typeparam>
+    /// <seealso cref="ShellContent" />
+    public class ShellViewModel<TViewModel> : ShellContent, IActivatableView
+        where TViewModel : class, new()
+    {
+        /// <summary>
+        /// The contract property.
+        /// </summary>
+        public static readonly BindableProperty ContractProperty = BindableProperty.Create(
+            nameof(Contract),
+            typeof(string),
+            typeof(ShellViewModel<TViewModel>),
+            null);
+
+        /// <summary>
+        /// The view model property.
+        /// </summary>
+        public static readonly BindableProperty ViewModelProperty = BindableProperty.Create(
+            nameof(ViewModel),
+            typeof(TViewModel),
+            typeof(ShellViewModel<TViewModel>),
+            default(TViewModel),
+            BindingMode.Default,
+            propertyChanged: ViewModelChanged);
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ShellViewModel{TViewModel}"/> class.
+        /// </summary>
+        public ShellViewModel()
+        {
+            ViewLocator = Locator.Current.GetService<IViewLocator>();
+            ViewModel = new TViewModel();
+        }
+
+        /// <summary>
+        /// Gets or sets the view model.
+        /// </summary>
+        /// <value>
+        /// The view model.
+        /// </value>
+        public TViewModel ViewModel
+        {
+            get => (TViewModel)GetValue(ViewModelProperty);
+            set => SetValue(ViewModelProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the contract.
+        /// </summary>
+        /// <value>
+        /// The contract.
+        /// </value>
+        public string Contract
+        {
+            get => (string)GetValue(ContractProperty);
+            set => SetValue(ContractProperty, value);
+        }
+
+        /// <summary>
+        /// Gets or sets the view locator.
+        /// </summary>
+        /// <value>
+        /// The view locator.
+        /// </value>
+        public IViewLocator? ViewLocator { get; set; }
+
+        private static void ViewModelChanged(BindableObject bindable, object oldValue, object newValue)
+        {
+            if (bindable is ShellViewModel<TViewModel> svm)
+            {
+                var view = svm.ViewLocator?.ResolveView(newValue as TViewModel, svm.Contract);
+                svm.ContentTemplate = new DataTemplate(() => view);
+            }
+        }
+    }
+}

From 6d17459bf75cff0692f9630e65587bc4c3200554 Mon Sep 17 00:00:00 2001
From: Chris Pulman <chris.pulman@yahoo.com>
Date: Tue, 29 Jun 2021 19:39:05 +0100
Subject: [PATCH 2/4] Updates to resolve queries refactored tests using
 Xamarin.Forms.Mocks

Rename ShellViewModel to ReactiveShellContent to keep in with other extended elements
---
 ...sts.cs => ActivatingReactivePagesTests.cs} |  76 ++++--
 .../Activation/Mocks/AppShell.xaml            |  12 +-
 ...tingViewModel2.cs => AppShellViewModel.cs} |   6 +-
 .../Activation/Mocks/ApplicationFixture.cs    |  73 ++++++
 .../Activation/Mocks/ContentPageView.cs       |   1 -
 .../Activation/Mocks/MockForms.cs             | 241 ------------------
 .../Activation/Mocks/ShellView.cs             |   1 -
 .../ReactiveUI.XamForms.Tests.csproj          |  33 +--
 .../ActivationForViewFetcher.cs               |  30 +++
 ...llViewModel.cs => ReactiveShellContent.cs} |  48 ++--
 10 files changed, 192 insertions(+), 329 deletions(-)
 rename src/ReactiveUI.XamForms.Tests/Activation/{ActivatingReactiveContentPageTests.cs => ActivatingReactivePagesTests.cs} (56%)
 rename src/ReactiveUI.XamForms.Tests/Activation/Mocks/{ActivatingViewModel2.cs => AppShellViewModel.cs} (85%)
 create mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/ApplicationFixture.cs
 delete mode 100644 src/ReactiveUI.XamForms.Tests/Activation/Mocks/MockForms.cs
 rename src/ReactiveUI.XamForms/{ShellViewModel.cs => ReactiveShellContent.cs} (61%)

diff --git a/src/ReactiveUI.XamForms.Tests/Activation/ActivatingReactiveContentPageTests.cs b/src/ReactiveUI.XamForms.Tests/Activation/ActivatingReactivePagesTests.cs
similarity index 56%
rename from src/ReactiveUI.XamForms.Tests/Activation/ActivatingReactiveContentPageTests.cs
rename to src/ReactiveUI.XamForms.Tests/Activation/ActivatingReactivePagesTests.cs
index d1db7a1b12..6372b20e03 100644
--- a/src/ReactiveUI.XamForms.Tests/Activation/ActivatingReactiveContentPageTests.cs
+++ b/src/ReactiveUI.XamForms.Tests/Activation/ActivatingReactivePagesTests.cs
@@ -3,7 +3,6 @@
 // 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 System.Threading.Tasks;
 using ReactiveUI.XamForms;
 using ReactiveUI.XamForms.Tests.Activation;
 using ReactiveUI.XamForms.Tests.Activation.Mocks;
@@ -16,31 +15,44 @@ namespace ReactiveUI.Tests
     /// <summary>
     /// Tests for activating views.
     /// </summary>
-    public class ActivatingReactiveContentPageTests
+    public class ActivatingReactivePagesTests : IClassFixture<ApplicationFixture<App>>
     {
+        private ApplicationFixture<App> _fixture;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ActivatingReactivePagesTests"/> class.
+        /// </summary>
+        /// <param name="fixture">The fixture.</param>
+        public ActivatingReactivePagesTests(ApplicationFixture<App> fixture)
+        {
+            _fixture = fixture;
+            Locator.CurrentMutable.Register(() => new ActivationForViewFetcher(), typeof(IActivationForViewFetcher));
+            Locator.CurrentMutable.Register<IViewFor<ShellViewModel>>(() => new ShellView());
+            Locator.CurrentMutable.Register<IViewFor<ContentPageViewModel>>(() => new ContentPageView());
+            Locator.CurrentMutable.Register<IViewFor<TabbedPageViewModel>>(() => new TabbedPageView());
+            Locator.CurrentMutable.Register<IViewFor<CarouselPageViewModel>>(() => new CarouselPageView());
+            Locator.CurrentMutable.Register<IViewFor<FlyOutPageViewModel>>(() => new FlyoutPageView());
+            _fixture.ActivateApp(new App());
+        }
+
         /// <summary>
         /// Tests to make sure that views generally activate.
         /// </summary>
         [Fact]
-        public void ActivatingReactiveContentPageTest()
+        public void ActivatingReactiveShellTest()
         {
-            var locator = new ModernDependencyResolver();
-            locator.InitializeSplat();
-            locator.InitializeReactiveUI();
-            locator.Register(() => new ActivationForViewFetcher(), typeof(IActivationForViewFetcher));
-            locator.Register<IViewFor<ShellViewModel>>(() => new ShellView());
-            locator.Register<IViewFor<ContentPageViewModel>>(() => new ContentPageView());
-            locator.Register<IViewFor<TabbedPageViewModel>>(() => new TabbedPageView());
-            locator.Register<IViewFor<CarouselPageViewModel>>(() => new CarouselPageView());
-            locator.Register<IViewFor<FlyOutPageViewModel>>(() => new FlyoutPageView());
-
-            MockForms.Init();
-            var app = new App();
-            var main = app.MainPage as AppShell;
+            var main = _fixture.AppMock!.MainPage as AppShell;
 
             Assert.Equal(1, main!.ViewModel!.IsActiveCount);
             Assert.Equal(1, main.IsActiveCount);
+        }
 
+        /// <summary>
+        /// Tests to make sure that views generally activate.
+        /// </summary>
+        [Fact]
+        public void ActivatingReactiveContentPageTest()
+        {
             var vm = new ContentPageViewModel();
             var fixture = new ContentPageView
             {
@@ -48,7 +60,7 @@ public void ActivatingReactiveContentPageTest()
             };
 
             // Activate
-            main.Navigation.PushAsync(fixture);
+            Shell.Current.Navigation.PushAsync(fixture);
             Assert.Equal(1, fixture.ViewModel.IsActiveCount);
             Assert.Equal(1, fixture.IsActiveCount);
 
@@ -57,7 +69,14 @@ public void ActivatingReactiveContentPageTest()
             fixture.ViewModel = null;
             Assert.Equal(0, vm.IsActiveCount);
             Assert.Equal(0, fixture.IsActiveCount);
+        }
 
+        /// <summary>
+        /// Tests to make sure that views generally activate.
+        /// </summary>
+        [Fact]
+        public void ActivatingReactiveTabbedPageTest()
+        {
             var vm1 = new TabbedPageViewModel();
             var fixture1 = new TabbedPageView
             {
@@ -65,7 +84,7 @@ public void ActivatingReactiveContentPageTest()
             };
 
             // Activate
-            main.Navigation.PushAsync(fixture1);
+            Shell.Current.Navigation.PushAsync(fixture1);
             Assert.Equal(1, fixture1.ViewModel.IsActiveCount);
             Assert.Equal(1, fixture1.IsActiveCount);
 
@@ -74,7 +93,14 @@ public void ActivatingReactiveContentPageTest()
             fixture1.ViewModel = null;
             Assert.Equal(0, vm1.IsActiveCount);
             Assert.Equal(0, fixture1.IsActiveCount);
+        }
 
+        /// <summary>
+        /// Tests to make sure that views generally activate.
+        /// </summary>
+        [Fact]
+        public void ActivatingReactiveFlyoutPageTest()
+        {
             var vm3 = new FlyOutPageViewModel();
             var fixture3 = new FlyoutPageView
             {
@@ -82,7 +108,7 @@ public void ActivatingReactiveContentPageTest()
             };
 
             // Activate
-            main.Navigation.PushAsync(fixture3);
+            Shell.Current.Navigation.PushAsync(fixture3);
             Assert.Equal(1, fixture3.ViewModel!.IsActiveCount);
             Assert.Equal(1, fixture3.IsActiveCount);
 
@@ -91,7 +117,14 @@ public void ActivatingReactiveContentPageTest()
             fixture3.ViewModel = null;
             Assert.Equal(0, vm3.IsActiveCount);
             Assert.Equal(0, fixture3.IsActiveCount);
+        }
 
+        /// <summary>
+        /// Tests to make sure that views generally activate.
+        /// </summary>
+        [Fact]
+        public void ActivatingReactiveCarouselPageTest()
+        {
             var vm4 = new CarouselPageViewModel();
             var fixture4 = new CarouselPageView
             {
@@ -99,7 +132,7 @@ public void ActivatingReactiveContentPageTest()
             };
 
             // Activate
-            main.Navigation.PushAsync(fixture4);
+            Shell.Current.Navigation.PushAsync(fixture4);
             Assert.Equal(1, fixture4.ViewModel!.IsActiveCount);
             Assert.Equal(1, fixture4.IsActiveCount);
 
@@ -108,9 +141,6 @@ public void ActivatingReactiveContentPageTest()
             fixture4.ViewModel = null;
             Assert.Equal(0, vm4.IsActiveCount);
             Assert.Equal(0, fixture4.IsActiveCount);
-
-            // remember to kill the app
-            app.Quit();
         }
     }
 }
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShell.xaml b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShell.xaml
index 18c67fc8a0..8378f7896b 100644
--- a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShell.xaml
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShell.xaml
@@ -6,7 +6,7 @@
     xmlns:rxui="clr-namespace:ReactiveUI.XamForms;assembly=ReactiveUI.XamForms"
     xmlns:vm="clr-namespace:ReactiveUI.XamForms.Tests.Activation"
     Title="Shell.XamForms.Test"
-    x:TypeArguments="vm:ActivatingViewModel2">
+    x:TypeArguments="vm:AppShellViewModel">
 
     <!--
         The overall app visual hierarchy is defined here, along with navigation.
@@ -31,9 +31,9 @@
         </ResourceDictionary>
     </Shell.Resources>
 
-    <rxui:ShellViewModel Title="Shell" x:TypeArguments="vm:ShellViewModel" />
-    <rxui:ShellViewModel Title="Content" x:TypeArguments="vm:ContentPageViewModel" />
-    <rxui:ShellViewModel Title="Tabbed" x:TypeArguments="vm:TabbedPageViewModel" />
-    <rxui:ShellViewModel Title="Carousel" x:TypeArguments="vm:CarouselPageViewModel" />
-    <rxui:ShellViewModel Title="FlyOut" x:TypeArguments="vm:FlyOutPageViewModel" />
+    <rxui:ReactiveShellContent Title="Shell" x:TypeArguments="vm:ShellViewModel" />
+    <rxui:ReactiveShellContent Title="Content" x:TypeArguments="vm:ContentPageViewModel" />
+    <rxui:ReactiveShellContent Title="Tabbed" x:TypeArguments="vm:TabbedPageViewModel" />
+    <rxui:ReactiveShellContent Title="Carousel" x:TypeArguments="vm:CarouselPageViewModel" />
+    <rxui:ReactiveShellContent Title="FlyOut" x:TypeArguments="vm:FlyOutPageViewModel" />
 </rxui:ReactiveShell>
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ActivatingViewModel2.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShellViewModel.cs
similarity index 85%
rename from src/ReactiveUI.XamForms.Tests/Activation/Mocks/ActivatingViewModel2.cs
rename to src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShellViewModel.cs
index fa94722b57..61cf138d8f 100644
--- a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ActivatingViewModel2.cs
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/AppShellViewModel.cs
@@ -12,12 +12,12 @@ namespace ReactiveUI.XamForms.Tests.Activation
     /// </summary>
     /// <seealso cref="ReactiveUI.ReactiveObject" />
     /// <seealso cref="ReactiveUI.IActivatableViewModel" />
-    public class ActivatingViewModel2 : ReactiveObject, IActivatableViewModel
+    public class AppShellViewModel : ReactiveObject, IActivatableViewModel
     {
         /// <summary>
-        /// Initializes a new instance of the <see cref="ActivatingViewModel2"/> class.
+        /// Initializes a new instance of the <see cref="AppShellViewModel"/> class.
         /// </summary>
-        public ActivatingViewModel2()
+        public AppShellViewModel()
         {
             Activator = new ViewModelActivator();
 
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ApplicationFixture.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ApplicationFixture.cs
new file mode 100644
index 0000000000..76d46cfcde
--- /dev/null
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ApplicationFixture.cs
@@ -0,0 +1,73 @@
+// Copyright (c) 2021 .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 System;
+using Splat;
+using Xamarin.Forms;
+using Xamarin.Forms.Mocks;
+
+namespace ReactiveUI.Tests
+{
+    /// <summary>
+    /// Application Fixture.
+    /// </summary>
+    /// <typeparam name="T">The Application Type.</typeparam>
+    /// <seealso cref="System.IDisposable" />
+    public class ApplicationFixture<T> : IDisposable
+        where T : Application
+    {
+        private bool _disposedValue;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ApplicationFixture{T}"/> class.
+        /// </summary>
+        public ApplicationFixture()
+        {
+            MockForms.Init();
+        }
+
+        /// <summary>
+        /// Gets the application.
+        /// </summary>
+        /// <value>
+        /// The application.
+        /// </value>
+        public T? AppMock { get; private set; }
+
+        /// <summary>
+        /// Activates this instance.
+        /// </summary>
+        /// <param name="app">The application.</param>
+        public void ActivateApp(T app) => AppMock = app;
+
+        /// <summary>
+        /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
+        /// </summary>
+        public void Dispose()
+        {
+            // Do not change this code. Put cleanup code in 'Dispose(bool disposing)' method
+            Dispose(disposing: true);
+            GC.SuppressFinalize(this);
+        }
+
+        /// <summary>
+        /// Releases unmanaged and - optionally - managed resources.
+        /// </summary>
+        /// <param name="disposing"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>
+        protected virtual void Dispose(bool disposing)
+        {
+            if (!_disposedValue)
+            {
+                if (disposing)
+                {
+                    AppMock?.Quit();
+                    Application.Current = null;
+                }
+
+                _disposedValue = true;
+            }
+        }
+    }
+}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ContentPageView.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ContentPageView.cs
index a91ad6492a..d2ae28d4bb 100644
--- a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ContentPageView.cs
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ContentPageView.cs
@@ -4,7 +4,6 @@
 // See the LICENSE file in the project root for full license information.
 
 using System.Reactive.Disposables;
-using ReactiveUI.Tests;
 
 namespace ReactiveUI.XamForms.Tests.Activation
 {
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/MockForms.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/MockForms.cs
deleted file mode 100644
index 264ba2f754..0000000000
--- a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/MockForms.cs
+++ /dev/null
@@ -1,241 +0,0 @@
-// Copyright (c) 2021 .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 System;
-using System.Collections.Generic;
-using System.IO;
-using System.Reflection;
-using System.Security.Cryptography;
-using System.Text;
-using System.Threading;
-using System.Threading.Tasks;
-using Xamarin.Forms;
-using Xamarin.Forms.Internals;
-
-namespace ReactiveUI.Tests
-{
-    /// <summary>
-    /// Mock Forms.
-    /// </summary>
-    public static class MockForms
-    {
-        /// <summary>
-        /// Initializes this instance.
-        /// </summary>
-        public static void Init()
-        {
-            Device.Info = new MockDeviceInfo();
-            Device.PlatformServices = new MockPlatformServices();
-
-            DependencyService.Register<MockResourcesProvider>();
-            DependencyService.Register<MockDeserializer>();
-        }
-
-        internal class MockPlatformServices : IPlatformServices
-        {
-            private Action<Action>? _invokeOnMainThread;
-            private Action<Uri>? _openUriAction;
-            private Func<Uri, CancellationToken, Task<Stream>>? _getStreamAsync;
-
-            public MockPlatformServices(Action<Action>? invokeOnMainThread = null, Action<Uri>? openUriAction = null, Func<Uri, CancellationToken, Task<Stream>>? getStreamAsync = null)
-            {
-                _invokeOnMainThread = invokeOnMainThread;
-                _openUriAction = openUriAction;
-                _getStreamAsync = getStreamAsync;
-            }
-
-            public bool IsInvokeRequired
-            {
-                get { return false; }
-            }
-
-            public string? RuntimePlatform { get; set; }
-
-            public OSAppTheme RequestedTheme => OSAppTheme.Dark;
-
-            public static int Hex(int v) => v < 10 ? '0' + v : 'a' + v - 10;
-
-            public void OpenUriAction(Uri uri)
-            {
-                if (_openUriAction != null)
-                {
-                    _openUriAction(uri);
-                }
-                else
-                {
-                    throw new NotImplementedException();
-                }
-            }
-
-            public void BeginInvokeOnMainThread(Action action)
-            {
-                if (_invokeOnMainThread == null)
-                {
-                    action();
-                }
-                else
-                {
-                    _invokeOnMainThread(action);
-                }
-            }
-
-            public string GetMD5Hash(string input)
-            {
-                // Step 1, calculate MD5 hash from input
-                var md5 = MD5.Create();
-                var inputBytes = Encoding.ASCII.GetBytes(input);
-                var hashBytes = md5.ComputeHash(inputBytes);
-
-                // Step 2, convert byte array to hex string
-                var sb = new StringBuilder();
-                for (var i = 0; i < hashBytes.Length; i++)
-                {
-                    sb.Append(hashBytes[i].ToString("X2"));
-                }
-
-                return sb.ToString();
-            }
-
-            public double GetNamedSize(NamedSize size, Type targetElement, bool useOldSizes)
-            {
-                switch (size)
-                {
-                    case NamedSize.Default:
-                        return 10;
-
-                    case NamedSize.Micro:
-                        return 4;
-
-                    case NamedSize.Small:
-                        return 8;
-
-                    case NamedSize.Medium:
-                        return 12;
-
-                    case NamedSize.Large:
-                        return 16;
-
-                    default:
-                        throw new ArgumentOutOfRangeException(nameof(size));
-                }
-            }
-
-            public Ticker CreateTicker() => new MockTicker();
-
-            public void StartTimer(TimeSpan interval, Func<bool> callback)
-            {
-                Timer? timer = null;
-                TimerCallback onTimeout = o => BeginInvokeOnMainThread(() =>
-                {
-                    if (callback())
-                    {
-                        return;
-                    }
-
-                    timer?.Dispose();
-                });
-                timer = new Timer(onTimeout, null, interval, interval);
-            }
-
-            public Task<Stream> GetStreamAsync(Uri uri, CancellationToken cancellationToken)
-            {
-                if (_getStreamAsync == null)
-                {
-                    throw new NotImplementedException();
-                }
-
-                return _getStreamAsync(uri, cancellationToken);
-            }
-
-            public Assembly[] GetAssemblies() => new Assembly[0];
-
-            public IIsolatedStorageFile GetUserStoreForApplication()
-            {
-                throw new NotImplementedException();
-            }
-
-            public string GetHash(string input) => throw new NotImplementedException();
-
-            public Color GetNamedColor(string name) => Color.DeepSkyBlue;
-
-            public void QuitApplication()
-            {
-            }
-
-            public SizeRequest GetNativeSize(VisualElement view, double widthConstraint, double heightConstraint) => throw new NotImplementedException();
-        }
-
-        internal class MockDeserializer : IDeserializer
-        {
-            public Task<IDictionary<string, object>> DeserializePropertiesAsync() =>
-                Task.FromResult<IDictionary<string, object>>(new Dictionary<string, object>());
-
-            public Task SerializePropertiesAsync(IDictionary<string, object> properties) =>
-                Task.FromResult(false);
-        }
-
-        internal class MockResourcesProvider : ISystemResourcesProvider
-        {
-            public IResourceDictionary GetSystemResources()
-            {
-                var dictionary = new ResourceDictionary();
-                Style style;
-                style = new Style(typeof(Label));
-                dictionary[Device.Styles.BodyStyleKey] = style;
-
-                style = new Style(typeof(Label));
-                style.Setters.Add(Label.FontSizeProperty, 50);
-                dictionary[Device.Styles.TitleStyleKey] = style;
-
-                style = new Style(typeof(Label));
-                style.Setters.Add(Label.FontSizeProperty, 40);
-                dictionary[Device.Styles.SubtitleStyleKey] = style;
-
-                style = new Style(typeof(Label));
-                style.Setters.Add(Label.FontSizeProperty, 30);
-                dictionary[Device.Styles.CaptionStyleKey] = style;
-
-                style = new Style(typeof(Label));
-                style.Setters.Add(Label.FontSizeProperty, 20);
-                dictionary[Device.Styles.ListItemTextStyleKey] = style;
-
-                style = new Style(typeof(Label));
-                style.Setters.Add(Label.FontSizeProperty, 10);
-                dictionary[Device.Styles.ListItemDetailTextStyleKey] = style;
-
-                return dictionary;
-            }
-        }
-
-        internal class MockTicker : Ticker
-        {
-            private bool _enabled;
-
-            protected override void EnableTimer()
-            {
-                _enabled = true;
-
-                while (_enabled)
-                {
-                    SendSignals(16);
-                }
-            }
-
-            protected override void DisableTimer()
-            {
-                _enabled = false;
-            }
-        }
-
-        internal class MockDeviceInfo : DeviceInfo
-        {
-            public override Size PixelScreenSize => throw new NotImplementedException();
-
-            public override Size ScaledScreenSize => throw new NotImplementedException();
-
-            public override double ScalingFactor => throw new NotImplementedException();
-        }
-    }
-}
diff --git a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ShellView.cs b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ShellView.cs
index d39d530fbc..b360fdec91 100644
--- a/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ShellView.cs
+++ b/src/ReactiveUI.XamForms.Tests/Activation/Mocks/ShellView.cs
@@ -4,7 +4,6 @@
 // See the LICENSE file in the project root for full license information.
 
 using System.Reactive.Disposables;
-using ReactiveUI.Tests;
 
 namespace ReactiveUI.XamForms.Tests.Activation
 {
diff --git a/src/ReactiveUI.XamForms.Tests/ReactiveUI.XamForms.Tests.csproj b/src/ReactiveUI.XamForms.Tests/ReactiveUI.XamForms.Tests.csproj
index d6e6fd28ed..7bb2161d6d 100644
--- a/src/ReactiveUI.XamForms.Tests/ReactiveUI.XamForms.Tests.csproj
+++ b/src/ReactiveUI.XamForms.Tests/ReactiveUI.XamForms.Tests.csproj
@@ -1,42 +1,15 @@
 <Project Sdk="Microsoft.NET.Sdk">
-
   <PropertyGroup>
     <TargetFramework>netcoreapp3.1</TargetFramework>
     <IsPackable>false</IsPackable>
+    <LangVersion>latest</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>
-    <ProjectReference Include="..\ReactiveUI.XamForms\ReactiveUI.XamForms.csproj" />
+    <PackageReference Include="Xamarin.Forms.Mocks" Version="4.7.0.1" />
   </ItemGroup>
 
   <ItemGroup>
-    <Compile Update="Activation\Mocks\FlyoutPageView.xaml.cs">
-      <DependentUpon>FlyoutPageView.xaml</DependentUpon>
-    </Compile>
-    <Compile Update="Activation\Mocks\FlyoutPageViewFlyout.xaml.cs">
-      <DependentUpon>FlyoutPageViewFlyout.xaml</DependentUpon>
-    </Compile>
-    <Compile Update="Activation\Mocks\FlyoutPageViewDetail.xaml.cs">
-      <DependentUpon>FlyoutPageViewDetail.xaml</DependentUpon>
-    </Compile>
-  </ItemGroup>
-
-  <ItemGroup>
-    <EmbeddedResource Update="Activation\Mocks\App.xaml">
-      <Generator>MSBuild:Compile</Generator>
-    </EmbeddedResource>
-    <EmbeddedResource Update="Activation\Mocks\AppShell.xaml">
-      <Generator>MSBuild:Compile</Generator>
-    </EmbeddedResource>
-    <EmbeddedResource Update="Activation\Mocks\FlyoutPageView.xaml">
-      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
-    </EmbeddedResource>
-    <EmbeddedResource Update="Activation\Mocks\FlyoutPageViewDetail.xaml">
-      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
-    </EmbeddedResource>
-    <EmbeddedResource Update="Activation\Mocks\FlyoutPageViewFlyout.xaml">
-      <Generator>MSBuild:UpdateDesignTimeXaml</Generator>
-    </EmbeddedResource>
+    <ProjectReference Include="..\ReactiveUI.XamForms\ReactiveUI.XamForms.csproj" />
   </ItemGroup>
-
 </Project>
diff --git a/src/ReactiveUI.XamForms/ActivationForViewFetcher.cs b/src/ReactiveUI.XamForms/ActivationForViewFetcher.cs
index e691e6cb46..4fa5652b6e 100644
--- a/src/ReactiveUI.XamForms/ActivationForViewFetcher.cs
+++ b/src/ReactiveUI.XamForms/ActivationForViewFetcher.cs
@@ -20,6 +20,7 @@ public class ActivationForViewFetcher : IActivationForViewFetcher
         /// <inheritdoc/>
         public int GetAffinityForView(Type view) =>
             typeof(Shell).GetTypeInfo().IsAssignableFrom(view.GetTypeInfo()) ||
+            typeof(BaseShellItem).GetTypeInfo().IsAssignableFrom(view.GetTypeInfo()) ||
             typeof(Page).GetTypeInfo().IsAssignableFrom(view.GetTypeInfo()) ||
             typeof(View).GetTypeInfo().IsAssignableFrom(view.GetTypeInfo()) ||
             typeof(Cell).GetTypeInfo().IsAssignableFrom(view.GetTypeInfo())
@@ -31,6 +32,7 @@ public IObservable<bool> GetActivationForView(IActivatableView view)
             var activation =
                 GetActivationFor(view as ICanActivate) ??
                 GetActivationFor(view as Shell) ??
+                GetActivationFor(view as BaseShellItem) ??
                 GetActivationFor(view as Page) ??
                 GetActivationFor(view as View) ??
                 GetActivationFor(view as Cell) ??
@@ -142,5 +144,33 @@ public IObservable<bool> GetActivationForView(IActivatableView view)
 
             return appearing.Merge(disappearing);
         }
+
+        private static IObservable<bool>? GetActivationFor(BaseShellItem? page)
+        {
+            if (page is null)
+            {
+                return null;
+            }
+
+            var appearing = Observable.FromEvent<EventHandler, bool>(
+                eventHandler =>
+                {
+                    void Handler(object? sender, EventArgs e) => eventHandler(true);
+                    return Handler;
+                },
+                x => page.Appearing += x,
+                x => page.Appearing -= x);
+
+            var disappearing = Observable.FromEvent<EventHandler, bool>(
+                eventHandler =>
+                {
+                    void Handler(object? sender, EventArgs e) => eventHandler(false);
+                    return Handler;
+                },
+                x => page.Disappearing += x,
+                x => page.Disappearing -= x);
+
+            return appearing.Merge(disappearing);
+        }
     }
 }
diff --git a/src/ReactiveUI.XamForms/ShellViewModel.cs b/src/ReactiveUI.XamForms/ReactiveShellContent.cs
similarity index 61%
rename from src/ReactiveUI.XamForms/ShellViewModel.cs
rename to src/ReactiveUI.XamForms/ReactiveShellContent.cs
index 99a295545a..c85ecf75d5 100644
--- a/src/ReactiveUI.XamForms/ShellViewModel.cs
+++ b/src/ReactiveUI.XamForms/ReactiveShellContent.cs
@@ -13,8 +13,8 @@ namespace ReactiveUI.XamForms
     /// </summary>
     /// <typeparam name="TViewModel">The type of the view model.</typeparam>
     /// <seealso cref="ShellContent" />
-    public class ShellViewModel<TViewModel> : ShellContent, IActivatableView
-        where TViewModel : class, new()
+    public class ReactiveShellContent<TViewModel> : ShellContent, IActivatableView
+        where TViewModel : class
     {
         /// <summary>
         /// The contract property.
@@ -22,8 +22,10 @@ public class ShellViewModel<TViewModel> : ShellContent, IActivatableView
         public static readonly BindableProperty ContractProperty = BindableProperty.Create(
             nameof(Contract),
             typeof(string),
-            typeof(ShellViewModel<TViewModel>),
-            null);
+            typeof(ReactiveShellContent<TViewModel>),
+            null,
+            BindingMode.Default,
+            propertyChanged: ViewModelChanged);
 
         /// <summary>
         /// The view model property.
@@ -31,18 +33,21 @@ public class ShellViewModel<TViewModel> : ShellContent, IActivatableView
         public static readonly BindableProperty ViewModelProperty = BindableProperty.Create(
             nameof(ViewModel),
             typeof(TViewModel),
-            typeof(ShellViewModel<TViewModel>),
+            typeof(ReactiveShellContent<TViewModel>),
             default(TViewModel),
             BindingMode.Default,
             propertyChanged: ViewModelChanged);
 
         /// <summary>
-        /// Initializes a new instance of the <see cref="ShellViewModel{TViewModel}"/> class.
+        /// Initializes a new instance of the <see cref="ReactiveShellContent{TViewModel}" /> class.
         /// </summary>
-        public ShellViewModel()
+        public ReactiveShellContent()
         {
-            ViewLocator = Locator.Current.GetService<IViewLocator>();
-            ViewModel = new TViewModel();
+            var view = Locator.Current.GetService<IViewFor<TViewModel>>(Contract);
+            if (view != null)
+            {
+                ContentTemplate = new DataTemplate(() => view);
+            }
         }
 
         /// <summary>
@@ -51,38 +56,33 @@ public ShellViewModel()
         /// <value>
         /// The view model.
         /// </value>
-        public TViewModel ViewModel
+        public TViewModel? ViewModel
         {
             get => (TViewModel)GetValue(ViewModelProperty);
             set => SetValue(ViewModelProperty, value);
         }
 
         /// <summary>
-        /// Gets or sets the contract.
+        /// Gets or sets the contract for the view.
         /// </summary>
         /// <value>
         /// The contract.
         /// </value>
-        public string Contract
+        public string? Contract
         {
-            get => (string)GetValue(ContractProperty);
+            get => (string?)GetValue(ContractProperty);
             set => SetValue(ContractProperty, value);
         }
 
-        /// <summary>
-        /// Gets or sets the view locator.
-        /// </summary>
-        /// <value>
-        /// The view locator.
-        /// </value>
-        public IViewLocator? ViewLocator { get; set; }
-
         private static void ViewModelChanged(BindableObject bindable, object oldValue, object newValue)
         {
-            if (bindable is ShellViewModel<TViewModel> svm)
+            if (bindable is ReactiveShellContent<TViewModel> svm)
             {
-                var view = svm.ViewLocator?.ResolveView(newValue as TViewModel, svm.Contract);
-                svm.ContentTemplate = new DataTemplate(() => view);
+                var view = Locator.Current.GetService<IViewFor<TViewModel>>(svm.Contract);
+                if (view != null)
+                {
+                    svm.ContentTemplate = new DataTemplate(() => view);
+                }
             }
         }
     }

From 8d47c1b4b3cb743a9c446875d36434c84d2b6cda Mon Sep 17 00:00:00 2001
From: Chris Pulman <chris.pulman@yahoo.com>
Date: Tue, 6 Jul 2021 21:03:44 +0100
Subject: [PATCH 3/4] Removed ReactiveMasterDetailPage is obsolete

---
 src/ReactiveUI.XamForms/ReactiveMasterDetailPage.cs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/ReactiveUI.XamForms/ReactiveMasterDetailPage.cs b/src/ReactiveUI.XamForms/ReactiveMasterDetailPage.cs
index a0880143cd..09ffb1bdc7 100644
--- a/src/ReactiveUI.XamForms/ReactiveMasterDetailPage.cs
+++ b/src/ReactiveUI.XamForms/ReactiveMasterDetailPage.cs
@@ -14,7 +14,6 @@ namespace ReactiveUI.XamForms
     /// <typeparam name="TViewModel">The type of the view model.</typeparam>
     /// <seealso cref="Xamarin.Forms.MasterDetailPage" />
     /// <seealso cref="ReactiveUI.IViewFor{TViewModel}" />
-    [Obsolete("ReactiveMasterDetailPage is obsolete as of version 5.0.0. Please use FlyoutPage instead.")]
     public class ReactiveMasterDetailPage<TViewModel> : MasterDetailPage, IViewFor<TViewModel>
         where TViewModel : class
     {

From 4572011cdcf589b954e063574bd8180d9dc5e045 Mon Sep 17 00:00:00 2001
From: Chris Pulman <chris.pulman@yahoo.com>
Date: Tue, 6 Jul 2021 21:11:11 +0100
Subject: [PATCH 4/4] throw new NullReferenceException(nameof(Locator.Current))
 if Locator.Current is null

---
 src/ReactiveUI.XamForms/ReactiveShellContent.cs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/ReactiveUI.XamForms/ReactiveShellContent.cs b/src/ReactiveUI.XamForms/ReactiveShellContent.cs
index c85ecf75d5..44cafac6d9 100644
--- a/src/ReactiveUI.XamForms/ReactiveShellContent.cs
+++ b/src/ReactiveUI.XamForms/ReactiveShellContent.cs
@@ -3,6 +3,7 @@
 // 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 System;
 using Splat;
 using Xamarin.Forms;
 
@@ -76,6 +77,11 @@ public string? Contract
 
         private static void ViewModelChanged(BindableObject bindable, object oldValue, object newValue)
         {
+            if (Locator.Current is null)
+            {
+                throw new NullReferenceException(nameof(Locator.Current));
+            }
+
             if (bindable is ReactiveShellContent<TViewModel> svm)
             {
                 var view = Locator.Current.GetService<IViewFor<TViewModel>>(svm.Contract);