Add tests for ellipse hit testing.

src/Avalonia.Visuals/Rendering/SceneGraph/EllipseNode.cs

@@ -109,7 +109,7 @@ namespace Avalonia.Rendering.SceneGraph
 
                 var distance = ry2 * dx * dx + rx2 * dy * dy;
 
-                return distance < rx2 * ry2;
+                return distance <= rx2 * ry2;
             }
 
             return false;

tests/Avalonia.Visuals.UnitTests/Rendering/SceneGraph/EllipseNodeTests.cs

@@ -0,0 +1,47 @@
+using Avalonia.Media;
+using Avalonia.Media.Immutable;
+using Avalonia.Rendering.SceneGraph;
+using Xunit;
+
+namespace Avalonia.Visuals.UnitTests.Rendering.SceneGraph
+{
+    public class EllipseNodeTests
+    {
+        [Theory]
+        [InlineData(50, 50, true)]
+        [InlineData(50, 0, true)]
+        [InlineData(100, 50, true)]
+        [InlineData(50, 100, true)]
+        [InlineData(-1, 0, false)]
+        [InlineData(101, 0, false)]
+        [InlineData(101, 101, false)]
+        [InlineData(0, 101, false)]
+        public void FillOnly_HitTest(double x, double y, bool inside)
+        {
+            var ellipseNode = new EllipseNode(Matrix.Identity, Brushes.Black, null, new Rect(0,0, 100, 100), null);
+
+            var point = new Point(x, y);
+
+            Assert.True(ellipseNode.HitTest(point) == inside);
+        }
+
+        [Theory]
+        [InlineData(50, 0, true)]
+        [InlineData(51, 0, true)]
+        [InlineData(100, 50, true)]
+        [InlineData(50, 100, true)]
+        [InlineData(-1, 50, true)]
+        [InlineData(53, 50, false)]
+        [InlineData(101, 0, false)]
+        [InlineData(101, 101, false)]
+        [InlineData(0, 101, false)]
+        public void StrokeOnly_HitTest(double x, double y, bool inside)
+        {
+            var ellipseNode = new EllipseNode(Matrix.Identity, null, new ImmutablePen(Brushes.Black, 2), new Rect(0, 0, 100, 100), null);
+
+            var point = new Point(x, y);
+
+            Assert.Equal(inside, ellipseNode.HitTest(point));
+        }
+    }
+}