Added a failing test for #1221

tests/Avalonia.Visuals.UnitTests/VisualTree/VisualExtensions_GetVisualsAt.cs

@@ -0,0 +1,103 @@
+using System;
+using System.Linq;
+using Avalonia.Controls;
+using Avalonia.Media;
+using Avalonia.Rendering;
+using Avalonia.UnitTests;
+using Avalonia.VisualTree;
+using Xunit;
+
+namespace Avalonia.Visuals.UnitTests.VisualTree
+{
+    public class VisualExtensions_GetVisualsAt
+    {
+        [Fact]
+        public void Should_Find_Control()
+        {
+            using (TestApplication())
+            {
+                Border target;
+                var root = new TestRoot
+                {
+                    Width = 200,
+                    Height = 200,
+                    Child = new StackPanel
+                    {
+                        Background = Brushes.White,
+                        Children =
+                        {
+                            (target = new Border
+                            {
+                                Width = 100,
+                                Height = 200,
+                                Background = Brushes.Red,
+                            }),
+                            new Border
+                            {
+                                Width = 100,
+                                Height = 200,
+                                Background = Brushes.Green,
+                            }
+                        },
+                        Orientation = Orientation.Horizontal,
+                    }
+                };
+
+                root.Renderer = new DeferredRenderer(root, null);
+                root.Measure(Size.Infinity);
+                root.Arrange(new Rect(root.DesiredSize));
+
+                var result = target.GetVisualsAt(new Point(50, 50));
+
+                Assert.Same(target, result.Single());
+            }
+        }
+
+        [Fact]
+        public void Should_Not_Find_Sibling_Control()
+        {
+            using (TestApplication())
+            {
+                Border target;
+                var root = new TestRoot
+                {
+                    Width = 200,
+                    Height = 200,
+                    Child = new StackPanel
+                    {
+                        Background = Brushes.White,
+                        Children =
+                        {
+                            (target = new Border
+                            {
+                                Width = 100,
+                                Height = 200,
+                                Background = Brushes.Red,
+                            }),
+                            new Border
+                            {
+                                Width = 100,
+                                Height = 200,
+                                Background = Brushes.Green,
+                            }
+                        },
+                        Orientation = Orientation.Horizontal,
+                    }
+                };
+
+                root.Renderer = new DeferredRenderer(root, null);
+                root.Measure(Size.Infinity);
+                root.Arrange(new Rect(root.DesiredSize));
+
+                var result = target.GetVisualsAt(new Point(150, 50));
+
+                Assert.Empty(result);
+            }
+        }
+
+        private IDisposable TestApplication()
+        {
+            return UnitTestApplication.Start(TestServices.MockPlatformRenderInterface);
+        }
+    }
+}