add failing test

tests/Avalonia.Base.UnitTests/Input/GesturesTests.cs

@@ -487,6 +487,40 @@ namespace Avalonia.Base.UnitTests.Input
             Assert.True(raised);
         }
 
+        [Fact]
+        public void Gestures_Should_Be_Cancelled_When_Pointer_Capture_Is_Lost()
+        {
+            Border border = new Border()
+            {
+                Width = 100,
+                Height = 100,
+                Background = new SolidColorBrush(Colors.Red)
+            };
+            border.GestureRecognizers.Add(new PinchGestureRecognizer());
+            var root = new TestRoot
+            {
+                Child = border
+            };
+            var raised = false;
+
+            root.AddHandler(Gestures.PinchEvent, (_, _) => raised = true);
+
+            var firstPoint = new Point(5, 5);
+            var secondPoint = new Point(10, 10);
+
+            var firstTouch = new TouchTestHelper();
+            var secondTouch = new TouchTestHelper();
+
+            firstTouch.Down(border, position: firstPoint);
+
+            firstTouch.Cancel();
+
+            secondTouch.Down(border, position: secondPoint);
+            secondTouch.Move(border, position: new Point(20, 20));
+
+            Assert.False(raised);
+        }
+
         [Fact]
         public void Scrolling_Should_Start_After_Start_Distance_Is_Exceeded()
         {

tests/Avalonia.UnitTests/TouchTestHelper.cs

@@ -61,5 +61,11 @@ namespace Avalonia.UnitTests
             Down(target, source, position, modifiers);
             Up(target, source, position, modifiers);
         }
+
+        public void Cancel()
+        {
+            _pointer.Capture(null);
+            _pointer.CaptureGestureRecognizer(null);
+        }
     }
 }