Add unit tests for DependencyObject extension methods

Author: w-ahmad

tests/DependencyObjectExtensionsTests.cs

@@ -0,0 +1,80 @@
+using Microsoft.UI.Xaml.Controls;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Microsoft.VisualStudio.TestTools.UnitTesting.AppContainer;
+using System.Linq;
+using System.Threading.Tasks;
+using WinUI.TableView.Extensions;
+
+namespace WinUI.TableView.Tests;
+
+[TestClass]
+public class DependencyObjectExtensionsTests
+{
+    private static Grid BuildVisualTree()
+    {
+        var root = new Grid();
+        var child1 = new StackPanel();
+        var child2 = new Button();
+        var grandChild = new TextBlock();
+        child1.Children.Add(grandChild);
+        root.Children.Add(child1);
+        root.Children.Add(child2);
+        return root;
+    }
+
+    [UITestMethod]
+    public void FindDescendant_FindsFirstMatchingType()
+    {
+        var root = BuildVisualTree();
+        var result = root.FindDescendant<TextBlock>();
+        Assert.IsNotNull(result);
+        Assert.IsInstanceOfType<TextBlock>(result);
+    }
+
+    [UITestMethod]
+    public void FindDescendant_WithPredicate_FindsCorrectDescendant()
+    {
+        var root = BuildVisualTree();
+        var result = root.FindDescendant<StackPanel>(sp => sp.Children.Count == 1);
+        Assert.IsNotNull(result);
+        Assert.IsInstanceOfType<StackPanel>(result);
+    }
+
+    [UITestMethod]
+    public void FindDescendants_EnumeratesAllDescendants()
+    {
+        var root = BuildVisualTree();
+        var descendants = root.FindDescendants().ToList();
+
+        Assert.IsTrue(descendants.OfType<StackPanel>().Any());
+        Assert.IsTrue(descendants.OfType<Button>().Any());
+        Assert.IsTrue(descendants.OfType<TextBlock>().Any());
+    }
+
+    [UITestMethod]
+    public async Task FindAscendant_FindsFirstMatchingAscendant()
+    {
+        var root = BuildVisualTree();
+        await UnitTestApp.Current.MainWindow.LoadTestContentAsync(root);
+
+        var grandChild = root.FindDescendant<TextBlock>();
+        var ascendant = grandChild?.FindAscendant<Grid>();
+        Assert.AreEqual(root, ascendant);
+
+        await UnitTestApp.Current.MainWindow.UnloadTestContentAsync(root);
+    }
+
+    [UITestMethod]
+    public async Task FindAscendants_EnumeratesAllAscendants()
+    {
+        var root = BuildVisualTree();
+        await UnitTestApp.Current.MainWindow.LoadTestContentAsync(root);
+
+        var grandChild = root.FindDescendant<TextBlock>();
+        var ascendants = grandChild?.FindAscendants().ToList();
+        Assert.IsTrue(ascendants?.OfType<StackPanel>().Any() ?? false);
+        Assert.IsTrue(ascendants?.OfType<Grid>().Any() ?? false);
+
+        await UnitTestApp.Current.MainWindow.UnloadTestContentAsync(root);
+    }
+}

tests/UnitTestApp.xaml.cs

@@ -1,21 +1,7 @@
 using Microsoft.UI.Xaml;
-using Microsoft.UI.Xaml.Controls;
-using Microsoft.UI.Xaml.Controls.Primitives;
-using Microsoft.UI.Xaml.Data;
-using Microsoft.UI.Xaml.Input;
-using Microsoft.UI.Xaml.Media;
-using Microsoft.UI.Xaml.Navigation;
-using Microsoft.UI.Xaml.Shapes;
+using Microsoft.VisualStudio.TestPlatform.TestExecutor;
 using Microsoft.VisualStudio.TestTools.UnitTesting.AppContainer;
 using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Runtime.InteropServices.WindowsRuntime;
-using Windows.ApplicationModel;
-using Windows.ApplicationModel.Activation;
-using Windows.Foundation;
-using Windows.Foundation.Collections;
 
 // To learn more about WinUI, the WinUI project structure,
 // and more about our project templates, see: http://aka.ms/winui-project-info.
@@ -26,7 +12,18 @@ namespace WinUI.TableView.Tests;
 /// </summary>
 public partial class UnitTestApp : Application
 {
-    private Window? _window;
+    private UnitTestAppWindow? _window;
+
+    internal static new UnitTestApp Current => (UnitTestApp)Application.Current;
+
+    internal UnitTestAppWindow MainWindow
+    {
+        get
+        {
+            _window ??= new UnitTestAppWindow();
+            return _window;
+        }
+    }
 
     /// <summary>
     /// Initializes the singleton application object.  This is the first line of authored code
@@ -43,13 +40,12 @@ public UnitTestApp()
     /// <param name="args">Details about the launch request and process.</param>
     protected override void OnLaunched(Microsoft.UI.Xaml.LaunchActivatedEventArgs args)
     {
-        Microsoft.VisualStudio.TestPlatform.TestExecutor.UnitTestClient.CreateDefaultUI();
+        UnitTestClient.CreateDefaultUI();
 
-        _window = new UnitTestAppWindow();
-        _window.Activate();
+        MainWindow.Activate();
 
-        UITestMethodAttribute.DispatcherQueue = _window.DispatcherQueue;
+        UITestMethodAttribute.DispatcherQueue = MainWindow.DispatcherQueue;
 
-        Microsoft.VisualStudio.TestPlatform.TestExecutor.UnitTestClient.Run(Environment.CommandLine);
+        UnitTestClient.Run(Environment.CommandLine);
     }
 }

tests/UnitTestAppWindow.xaml.cs

@@ -1,26 +1,70 @@
 using Microsoft.UI.Xaml;
-using Microsoft.UI.Xaml.Controls;
-using Microsoft.UI.Xaml.Controls.Primitives;
-using Microsoft.UI.Xaml.Data;
-using Microsoft.UI.Xaml.Input;
 using Microsoft.UI.Xaml.Media;
-using Microsoft.UI.Xaml.Navigation;
-using System;
-using System.Collections.Generic;
-using System.IO;
-using System.Linq;
-using System.Runtime.InteropServices.WindowsRuntime;
-using Windows.Foundation;
-using Windows.Foundation.Collections;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using System.Threading.Tasks;
 
 // To learn more about WinUI, the WinUI project structure,
 // and more about our project templates, see: http://aka.ms/winui-project-info.
 
 namespace WinUI.TableView.Tests;
+
 public sealed partial class UnitTestAppWindow : Window
 {
     public UnitTestAppWindow()
     {
         InitializeComponent();
     }
+
+    internal async Task LoadTestContentAsync(FrameworkElement content)
+    {
+        var taskCompletionSource = new TaskCompletionSource<object?>();
+
+        content.Loaded += OnLoaded;
+        Content = content;
+
+        await taskCompletionSource.Task;
+
+        async void OnLoaded(object sender, RoutedEventArgs args)
+        {
+            content.Loaded -= OnLoaded;
+
+            // Wait for first Render pass
+            await ExecuteAfterCompositionRenderingAsync();
+
+            taskCompletionSource.SetResult(null);
+        }
+    }
+
+    private static async Task ExecuteAfterCompositionRenderingAsync()
+    {
+        var taskCompletionSource = new TaskCompletionSource<object?>();
+
+        void Callback(object? sender, object args)
+        {
+            CompositionTarget.Rendering -= Callback;
+            taskCompletionSource.SetResult(null);
+        }
+
+        CompositionTarget.Rendering += Callback;
+
+        await taskCompletionSource.Task;
+    }
+
+    public async Task UnloadTestContentAsync(FrameworkElement element)
+    {
+        var taskCompletionSource = new TaskCompletionSource<object?>();
+
+        element.Unloaded += OnUnloaded;
+
+        Content = null;
+
+        await taskCompletionSource.Task;
+        Assert.IsFalse(element.IsLoaded);
+
+        void OnUnloaded(object sender, RoutedEventArgs args)
+        {
+            element.Unloaded -= OnUnloaded;
+            taskCompletionSource.SetResult(null);
+        }
+    }
 }