- add tests and fix failures

src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellFlyoutTemplatedContentRenderer.cs

@@ -127,6 +127,14 @@ protected virtual void LoadView(IShellContext shellContext)
 
 				void InitialLoad(GenericGlobalLayoutListener listener, AView view)
 				{
+					// This means the handler was disconnected before the flyout was loaded
+					if (_shellContext?.Shell is null)
+					{
+						listener.Invalidate();
+						sfl.LayoutChanging -= OnFlyoutViewLayoutChanging;
+						return;
+					}
+
 					OnFlyoutViewLayoutChanging();
 
 					if (_flyoutContentView == null || ggll == null)

src/Controls/src/Core/Shell/ShellContent.cs

@@ -249,8 +249,8 @@ shellSection.Parent is ShellItem shellItem &&
 
 			if (_contentCache is not null)
 			{
-				RemoveLogicalChild(_contentCache);
 				_contentCache.Unloaded -= OnPageUnloaded;
+				RemoveLogicalChild(_contentCache);
 			}
 
 			_contentCache = null;

src/Controls/tests/TestCases.HostApp/Issues/Shell/ShellTransientTests.cs

@@ -4,21 +4,72 @@
 
 namespace Maui.Controls.Sample.Issues
 {
-	[Issue(IssueTracker.None, 0, "Navigating Between Transient Shell States Recreates Pages")]
+	[Issue(IssueTracker.None, 0, "Validate Basic Service Lifetime Behavior On Shell")]
 	public class ShellTransientTests : Shell
 	{
-        List<ContentPage> _contentPages = new List<ContentPage>();
+        static List<ContentPage> _contentPages = new List<ContentPage>();
 		protected override void OnNavigated(ShellNavigatedEventArgs args)
 		{
 			base.OnNavigated(args);
+            LoadCurrentPage();
+		}
+
+        void LoadCurrentPage()
+        {
+            var navigatetoTransientPage = new Button 
+            { 
+                Text = "Navigate to transient page", 
+                AutomationId = "NavigateToTransientPage",
+                Command = new Command(() => 
+                {
+                    ((ContentPage)this.CurrentPage).Content = new Label(){ Text = "Navigating. If you tried to navigate to the same page type, you'll be stuck here."};
+                    this.CurrentItem = Items[0];
+                })
+            };
+
+            var navigateToNotRegisteredPage = new Button 
+            { 
+                Text = "Navigate to Unregistered page", 
+                AutomationId = "NavigateToUnregisteredPage",
+                Command = new Command(() => 
+                {
+                    ((ContentPage)this.CurrentPage).Content = new Label(){ Text = "Navigating. If you tried to navigate to the same page type, you'll be stuck here."};
+                    this.CurrentItem = Items[1];
+                })
+            };
+
+            var navigateToScopedPage = new Button 
+            { 
+                Text = "Navigate to scoped page", 
+                AutomationId = "NavigateToScopedPage",
+                Command = new Command(() => 
+                {
+                    ((ContentPage)this.CurrentPage).Content = new Label(){ Text = "Navigating. If you tried to navigate to the same page type, you'll be stuck here."};
+                    this.CurrentItem = Items[2];
+                })
+            };
+
+            var navigateToNewShell = new Button 
+            { 
+                Text = "Navigate to New Shell", 
+                AutomationId = "NavigateToNewShell",
+                Command = new Command(() => 
+                {
+                    this.Window.Page = new ShellTransientTests();
+                })
+            };
 
             if (_contentPages.Contains(this.CurrentPage))
             {
                 (CurrentPage as ContentPage).Content = new VerticalStackLayout()
                 {
                     Children =
                     {
-                        new Label { Text = "Test Failed I am not a new page", AutomationId = "Failure" }
+                        navigatetoTransientPage,
+                        navigateToNotRegisteredPage,
+                        navigateToScopedPage,
+                        navigateToNewShell,
+                        new Label { Text = "I am not a new page", AutomationId = "OldPage" }
                     }
                 };
             }
@@ -28,13 +79,17 @@ protected override void OnNavigated(ShellNavigatedEventArgs args)
                 {
                     Children =
                     {
-                        new Label { Text = "I am a new page", AutomationId = "Success" }
+                        navigatetoTransientPage,
+                        navigateToNotRegisteredPage,
+                        navigateToScopedPage,
+                        navigateToNewShell,
+                        new Label { Text = "I am a new page", AutomationId = "NewPage" }
                     }
                 };
             }
 
             _contentPages.Add((ContentPage)this.CurrentPage);
-		}
+        }
 
 		public ShellTransientTests()
         {
@@ -43,20 +98,19 @@ public ShellTransientTests()
                 ContentTemplate = new DataTemplate(typeof(TransientPage))
             };
 
-
             var shellContent2 = new ShellContent()
             {
-                ContentTemplate = new DataTemplate(typeof(TransientPage))
+                ContentTemplate = new DataTemplate(typeof(ContentPage))
             };
 
             var shellContent3 = new ShellContent()
             {
-                ContentTemplate = new DataTemplate(typeof(ContentPage))
+                ContentTemplate = new DataTemplate(typeof(ScopedPage))
             };
 
             Items.Add(new FlyoutItem()
             {
-                Title = "Flyout Item 1",
+                Title = "Transient Page",
                 Items =
                 {
                     shellContent1
@@ -65,17 +119,16 @@ public ShellTransientTests()
 
             Items.Add(new FlyoutItem()
             {
-                Title = "Flyout Item 2",
+                Title = "Not Registered Page",
                 Items =
                 {
                     shellContent2
                 }
             });
 
-
             Items.Add(new FlyoutItem()
             {
-                Title = "Flyout Item 3",
+                Title = "Scoped Page",
                 Items =
                 {
                     shellContent3

src/Controls/tests/TestCases.HostApp/MauiProgram.cs

@@ -25,6 +25,8 @@ public static MauiApp CreateMauiApp()
 				})
 				.Issue21109AddMappers();
 
+			appBuilder.Services.AddTransient<TransientPage>();
+			appBuilder.Services.AddScoped<ScopedPage>();
 			return appBuilder.Build();
 		}
 	}

src/Controls/tests/TestCases.HostApp/ScopedPage.cs

@@ -0,0 +1,15 @@
+
+namespace Maui.Controls.Sample;
+
+public class ScopedPage : ContentPage
+{
+    static int i = 0;
+    public ScopedPage()
+    {
+        Index = i;
+        Content = new Label { Text = $"I'm a scoped page: {Index}" };
+        i++;
+    }
+
+    public int Index {get; private set;}
+}

src/Controls/tests/TestCases.HostApp/TransientPage.cs

@@ -0,0 +1,15 @@
+
+namespace Maui.Controls.Sample;
+
+public class TransientPage : ContentPage
+{
+    static int i = 0;
+    public TransientPage()
+    {
+        Index = i;
+        Content = new Label { Text = $"I'm a transient page: {Index}" };
+        i++;
+    }
+
+    public int Index {get; private set;}
+}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Shell/ShellTransientTests.cs

@@ -0,0 +1,70 @@
+using Microsoft.Maui.TestCases.Tests;
+using NUnit.Framework;
+using NUnit.Framework.Legacy;
+using UITest.Appium;
+using UITest.Core;
+
+namespace Microsoft.Maui.TestCases.Tests.Issues
+{
+	public partial class ShellTransientTests : _IssuesUITest
+	{
+		public ShellTransientTests(TestDevice device) : base(device) { }
+
+		public override string Issue => "Validate Basic Service Lifetime Behavior On Shell";
+
+		protected override bool ResetAfterEachTest => true;
+
+		[Test]
+		[Category(UITestCategories.Shell)]
+		public void ValidateBasicServiceLifetimePageBehavior()
+		{			
+			// Navigate to Transient Page for the First time
+			App.WaitForElement("NewPage");
+
+			// Navigate to Unregistered Page
+			App.WaitForElement("NavigateToUnregisteredPage");
+			App.Tap("NavigateToUnregisteredPage");
+			App.WaitForElement("NewPage", "New Page Not Created For Initial Navigation to Unregistered Page");
+
+			// Navigate to Scoped Page for the First time
+			App.WaitForElement("NavigateToScopedPage");
+			App.Tap("NavigateToScopedPage");
+			App.WaitForElement("NewPage", "New Page Not Created For Initial Navigation to Scoped Page");
+
+			// Navigate to Transient Page for the Second time
+			App.WaitForElement("NavigateToTransientPage");
+			App.Tap("NavigateToTransientPage");
+			App.WaitForElement("NewPage", "New Page Not Created For Second Navigation To Transient Page");
+
+			// Navigate to Transient Page for the Second time
+			App.WaitForElement("NavigateToScopedPage");
+			App.Tap("NavigateToScopedPage");
+			App.WaitForElement("OldPage", "New Page Incorrectly Created For Scoped Page");
+
+			// Navigate to Unregistered Page
+			App.WaitForElement("NavigateToUnregisteredPage");
+			App.Tap("NavigateToUnregisteredPage");
+			App.WaitForElement("OldPage", "New Page Incorrectly Created For Unregistered Page");
+		}
+
+		[Test]
+		[Category(UITestCategories.Shell)]
+		public void SwappingShellInstancesRecreatesPages()
+		{
+			// Navigate to Scoped Page so we can test that it's resued in Swapped Shell
+			App.WaitForElement("NavigateToScopedPage");
+			App.Tap("NavigateToScopedPage");
+			App.WaitForElement("NewPage", "New Page Not Created For Initial Navigation to Scoped Page");
+
+			// Verify New Page Created for Transient Page
+			App.WaitForElement("NewPage");
+			App.Tap("NavigateToNewShell");
+			App.WaitForElement("NewPage");
+
+			// Navigate to Scoped Page on Second Shell
+			App.WaitForElement("NavigateToScopedPage");
+			App.Tap("NavigateToScopedPage");
+			App.WaitForElement("OldPage", "New Page Incorrectly Created For Scoped Page");
+		}
+	}
+}