Add more test cases to try and track issue for #107

Author: michael-hawker

components/Extensions/tests/Element/FrameworkElementExtensionsTests.RelativeAncestor.cs

@@ -27,4 +27,128 @@ public void FrameworkElementExtension_RelativeAncestor_InDataTemplate(FrameworkE
 
         Assert.AreEqual(3, count, "Didn't find three textblocks");
     }
+
+    [TestCategory("FrameworkElementExtension")]
+    [UIThreadTestMethod]
+    public async Task FrameworkElementExtension_RelativeAncestor_FreeParentBaseline(FrameworkElementRelativeAncestorDataTemplateTestPage page)
+    {
+        var text = page.FindDescendant<TextBox>();
+
+        Assert.IsNotNull(text, "Couldn't find TextBox");
+
+        // Grab a hold of a weak reference for TextBox so we can detect when it unloads.
+        WeakReference textRef = new(text);
+        text = null;
+
+        var parent = page.FindDescendant<Grid>();
+
+        Assert.IsNotNull(parent, "Couldn't find parent Grid");
+
+        // Remove all the children from the grid to simulate it unloading.
+        VisualTreeHelper.DisconnectChildrenRecursive(parent);
+        parent.Children.Clear();
+        parent = null;
+
+        // Wait for the Visual Tree to perform removals and clean-up
+        await CompositionTargetHelper.ExecuteAfterCompositionRenderingAsync(() => { });
+
+        // Wait for the .NET Garbage Collector to clean up references
+        GC.Collect();
+        GC.WaitForPendingFinalizers();
+
+        Assert.IsFalse(textRef.IsAlive, "TextBox is still alive...");
+    }
+
+    [TestCategory("FrameworkElementExtension")]
+    [UIThreadTestMethod]
+    public async Task FrameworkElementExtension_RelativeAncestor_FreeParent(FrameworkElementRelativeAncestorDataTemplateTestPage page)
+    {
+        var list = page.FindDescendant<ListView>();
+
+        Assert.IsNotNull(list, "Couldn't find listview");
+
+        // Grab a hold of a weak reference for ListView so we can detect when it unloads.
+        WeakReference listRef = new(list);
+        list = null;
+
+        // Remove all the children from the grid to simulate it unloading.
+        VisualTreeHelper.DisconnectChildrenRecursive(page);
+        page.Content = null;
+
+        // Wait for the Visual Tree to perform removals and clean-up
+        await CompositionTargetHelper.ExecuteAfterCompositionRenderingAsync(() => { });
+
+        // Wait for the .NET Garbage Collector to clean up references
+        GC.Collect();
+        GC.WaitForPendingFinalizers();
+
+        Assert.IsFalse(listRef.IsAlive, "ListView is still alive...");
+    }
+
+    [TestCategory("FrameworkElementExtension")]
+    [UIThreadTestMethod]
+    public async Task FrameworkElementExtension_RelativeAncestor_FreePageNavigation()
+    {
+        TaskCompletionSource<bool?> taskCompletionSource = new();
+        var frame = new Frame();
+        frame.Navigated += OnNavigated;
+
+        await LoadTestContentAsync(frame);
+
+        // Navigate to the new page.
+        frame.Navigate(typeof(FrameworkElementRelativeAncestorDataTemplateTestPage), null, new SuppressNavigationTransitionInfo());
+
+        async void OnNavigated(object sender, NavigationEventArgs e)
+        {
+            frame.Navigated -= OnNavigated;
+
+            // Wait for first Render pass
+            await CompositionTargetHelper.ExecuteAfterCompositionRenderingAsync(() => { });
+
+            taskCompletionSource.SetResult(true);
+        }
+
+        // Wait for frame to navigate/load
+        var result = await taskCompletionSource.Task;
+        Assert.IsTrue(result, "Navigation didn't complete");
+
+        // Find the ListView we want to track
+
+        var list = frame.FindDescendant<ListView>();
+
+        Assert.IsNotNull(list, "Couldn't find listview");
+
+        // Grab a hold of a weak reference for ListView so we can detect when it unloads.
+        WeakReference listRef = new(list);
+        list = null;
+
+        TaskCompletionSource<bool?> taskCompletionSource2 = new();
+        frame.Navigated += OnNavigated2;
+
+        async void OnNavigated2(object sender, NavigationEventArgs e)
+        {
+            frame.Navigated -= OnNavigated2;
+
+            // Wait for first Render pass
+            await CompositionTargetHelper.ExecuteAfterCompositionRenderingAsync(() => { });
+
+            taskCompletionSource2.SetResult(true);
+        }
+
+        // Navigate to any other page to unload our other one
+        frame.Navigate(typeof(BitmapIconExtensionTestPage), null, new SuppressNavigationTransitionInfo());
+
+        // Wait for navigation to complete
+        result = await taskCompletionSource2.Task;
+        Assert.IsTrue(result, "Navigation didn't complete 2");
+
+        // Wait for the Visual Tree to perform removals and clean-up
+        await CompositionTargetHelper.ExecuteAfterCompositionRenderingAsync(() => { });
+
+        // Wait for the .NET Garbage Collector to clean up references
+        GC.Collect();
+        GC.WaitForPendingFinalizers();
+
+        Assert.IsFalse(listRef.IsAlive, "ListView is still alive...");
+    }
 }

components/Extensions/tests/Element/FrameworkElementRelativeAncestorDataTemplateTestPage.xaml

@@ -8,8 +8,7 @@
       mc:Ignorable="d">
 
     <Grid>
-        <ListView x:Name="ListViewControl"
-                  Tag="Hello">
+        <ListView Tag="Hello">
             <ListView.ItemTemplate>
                 <DataTemplate>
                     <TextBlock ui:FrameworkElementExtensions.AncestorType="ListView"
@@ -20,5 +19,7 @@
             <x:String>2</x:String>
             <x:String>3</x:String>
         </ListView>
+        <!--  Another child to test clearing GC  -->
+        <TextBox />
     </Grid>
 </Page>