[release/11.0.1xx-preview7] Stabilize unloaded page alert UI test

src/Controls/tests/TestCases.HostApp/Issues/Issue33287.cs

@@ -1,5 +1,5 @@
 using System;
-using System.Threading.Tasks;
+using System.ComponentModel;
 
 namespace Maui.Controls.Sample.Issues;
 
@@ -17,6 +17,12 @@ public Issue33287MainPage()
 	{
 		Title = "Issue 33287";
 
+		var statusLabel = new Label
+		{
+			Text = "Waiting for alert request",
+			AutomationId = "AlertStatusLabel"
+		};
+
 		Content = new VerticalStackLayout
 		{
 			Padding = 20,
@@ -28,23 +34,26 @@ public Issue33287MainPage()
 					Text = "Navigate to Second Page",
 					AutomationId = "NavigateButton",
 					Command = new Command(async () =>
-						await Navigation.PushAsync(new Issue33287SecondPage()))
+						await Navigation.PushAsync(new Issue33287SecondPage(status =>
+							statusLabel.Text = status)))
 				},
 				new Label
 				{
 					Text = "MainPage",
 					AutomationId = "MainPageLabel"
-				}
+				},
+				statusLabel
 			}
 		};
 	}
 }
 
 public class Issue33287SecondPage : ContentPage
 {
-	public Issue33287SecondPage()
+	public Issue33287SecondPage(Action<string> updateStatus)
 	{
 		Title = "Second Page";
+		PropertyChanged += OnPropertyChanged;
 
 		Content = new VerticalStackLayout
 		{
@@ -59,20 +68,18 @@ public Issue33287SecondPage()
 				}
 			}
 		};
-	}
 
-	protected override async void OnAppearing()
-	{
-		base.OnAppearing();
+		async void OnPropertyChanged(object sender, PropertyChangedEventArgs e)
+		{
+			if (e.PropertyName != nameof(Window) || Window is not null)
+				return;
 
-		// Wait long enough for the user/test to navigate back
-#if MACCATALYST
-		await Task.Delay(4000);
-#else
-		await Task.Delay(2000);
-#endif
+			PropertyChanged -= OnPropertyChanged;
+			updateStatus("Page detached");
 
-		// Without the fix this throws NullReferenceException and crashes the app
-		await DisplayAlertAsync("Test Alert", "This alert was delayed", "OK");
+			// Request the alert before handler teardown changes IsPlatformEnabled.
+			await DisplayAlertAsync("Test Alert", "This alert was delayed", "OK");
+			updateStatus("Alert request completed");
+		}
 	}
 }

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue33287.cs

@@ -23,12 +23,18 @@ public void DisplayAlertAsyncShouldNotCrashWhenPageUnloaded()
 		App.WaitForElement("GoBackButton");
 		App.Tap("GoBackButton");
 
-		// Back on main page — wait for the delayed DisplayAlertAsync to fire.
-		// Without the fix the NRE crashes the app and this element becomes unreachable.
+		// Back on the main page, wait until the detached page's alert request completes.
+		// Without the fix the NRE crashes the app and this status is never updated.
 		App.WaitForElement("MainPageLabel");
-		System.Threading.Thread.Sleep(3000);
-
-		// Verify the app is still alive and responsive after the alert fired on the detached page.
+		Assert.That(
+			App.WaitForTextToBePresentInElement(
+				"AlertStatusLabel",
+				"Alert request completed",
+				timeout: TimeSpan.FromSeconds(10)),
+			Is.True,
+			"The detached page's alert request should complete");
+
+		// Verify the app is still alive and responsive after the alert request on the detached page.
 		// Without the fix the app process is dead and this call will throw/timeout.
 		Assert.That(App.FindElement("MainPageLabel").GetText(), Is.EqualTo("MainPage"),
 			"App should remain responsive after DisplayAlertAsync on an unloaded page");