Add resampler unit test with widget (#64424)

packages/flutter/test/gestures/gesture_binding_resample_event_on_widget_test.dart

+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// @dart = 2.8
+
+// Logically this file should be part of `gesture_binding_test.dart` but is here
+// due to conflict of `flutter_test` and `package:test`.
+// See https://github.com/dart-lang/matcher/issues/98
+// TODO(CareF): Consider combine this file back to `gesture_binding_test.dart`
+// after #98 is fixed.
+
+import 'dart:ui' as ui;
+
+import 'package:flutter/gestures.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+class PointerDataAutomatedTestWidgetsFlutterBinding extends AutomatedTestWidgetsFlutterBinding {
+  // PointerData injection would usually considerred device input and therefore
+  // blocked by [AutomatedTestWidgetsFlutterBinding]. Override this behavior
+  // to help events go into widget tree.
+  @override
+  void dispatchEvent(
+    PointerEvent event,
+    HitTestResult hitTestResult, {
+    TestBindingEventSource source = TestBindingEventSource.device,
+  }) {
+    super.dispatchEvent(event, hitTestResult, source: TestBindingEventSource.test);
+  }
+}
+
+void main() {
+  final TestWidgetsFlutterBinding binding = PointerDataAutomatedTestWidgetsFlutterBinding();
+  testWidgets('PointerEvent resampling on a widget', (WidgetTester tester) async {
+    assert(WidgetsBinding.instance == binding);
+    Duration currentTestFrameTime() => Duration(milliseconds: binding.clock.now().millisecondsSinceEpoch);
+    final Duration epoch = currentTestFrameTime();
+    final ui.PointerDataPacket packet = ui.PointerDataPacket(
+      data: <ui.PointerData>[
+        ui.PointerData(
+            change: ui.PointerChange.add,
+            physicalX: 0.0,
+            timeStamp: epoch + const Duration(milliseconds: 0),
+        ),
+        ui.PointerData(
+            change: ui.PointerChange.down,
+            physicalX: 0.0,
+            timeStamp: epoch + const Duration(milliseconds: 1),
+        ),
+        ui.PointerData(
+            change: ui.PointerChange.move,
+            physicalX: 10.0,
+            timeStamp: epoch + const Duration(milliseconds: 2),
+        ),
+        ui.PointerData(
+            change: ui.PointerChange.move,
+            physicalX: 20.0,
+            timeStamp: epoch + const Duration(milliseconds: 3),
+        ),
+        ui.PointerData(
+            change: ui.PointerChange.move,
+            physicalX: 30.0,
+            timeStamp: epoch + const Duration(milliseconds: 4),
+        ),
+        ui.PointerData(
+            change: ui.PointerChange.up,
+            physicalX: 40.0,
+            timeStamp: epoch + const Duration(milliseconds: 5),
+        ),
+        ui.PointerData(
+            change: ui.PointerChange.remove,
+            physicalX: 40.0,
+            timeStamp: epoch + const Duration(milliseconds: 6),
+        ),
+      ],
+    );
+
+    final List<PointerEvent> events = <PointerEvent>[];
+    await tester.pumpWidget(
+      Directionality(
+        textDirection: TextDirection.ltr,
+        child: Listener(
+          onPointerDown: (PointerDownEvent event) => events.add(event),
+          onPointerMove: (PointerMoveEvent event) => events.add(event),
+          onPointerUp: (PointerUpEvent event) => events.add(event),
+          child: const Text('test'),
+        ),
+      ),
+    );
+
+    GestureBinding.instance.resamplingEnabled = true;
+    const Duration kSamplingOffset = Duration(microseconds: -5500);
+    GestureBinding.instance.samplingOffset = kSamplingOffset;
+    ui.window.onPointerDataPacket(packet);
+    expect(events.length, 0);
+
+    await tester.pump(const Duration(milliseconds: 7));
+    expect(events.length, 1);
+    expect(events[0].runtimeType, equals(PointerDownEvent));
+    expect(events[0].timeStamp, currentTestFrameTime() + kSamplingOffset);
+    expect(events[0].position, Offset(5.0 / ui.window.devicePixelRatio, 0.0));
+
+    // Now the system time is epoch + 9ms
+    await tester.pump(const Duration(milliseconds: 2));
+    expect(events.length, 2);
+    expect(events[1].timeStamp, currentTestFrameTime() + kSamplingOffset);
+    expect(events[1].runtimeType, equals(PointerMoveEvent));
+    expect(events[1].position, Offset(25.0 / ui.window.devicePixelRatio, 0.0));
+    expect(events[1].delta, Offset(20.0 / ui.window.devicePixelRatio, 0.0));
+
+    // Now the system time is epoch + 11ms
+    await tester.pump(const Duration(milliseconds: 2));
+    expect(events.length, 3);
+    expect(events[2].timeStamp, currentTestFrameTime() + kSamplingOffset);
+    expect(events[2].runtimeType, equals(PointerUpEvent));
+    expect(events[2].position, Offset(40.0 / ui.window.devicePixelRatio, 0.0));
+  });
+}

packages/flutter/test/gestures/gesture_binding_test.dart

@@ -315,107 +315,4 @@ void main() {
       expect(events[4].buttons, equals(0));
     }
   });
-
-  test('Pointer event resampling', () {
-    const ui.PointerDataPacket packet = ui.PointerDataPacket(
-      data: <ui.PointerData>[
-        ui.PointerData(
-            change: ui.PointerChange.add,
-            physicalX: 0.0,
-            timeStamp: Duration(milliseconds: 0),
-        ),
-        ui.PointerData(
-            change: ui.PointerChange.down,
-            physicalX: 0.0,
-            timeStamp: Duration(milliseconds: 1),
-        ),
-        ui.PointerData(
-            change: ui.PointerChange.move,
-            physicalX: 10.0,
-            timeStamp: Duration(milliseconds: 2),
-        ),
-        ui.PointerData(
-            change: ui.PointerChange.move,
-            physicalX: 20.0,
-            timeStamp: Duration(milliseconds: 3),
-        ),
-        ui.PointerData(
-            change: ui.PointerChange.move,
-            physicalX: 30.0,
-            timeStamp: Duration(milliseconds: 4),
-        ),
-        ui.PointerData(
-            change: ui.PointerChange.up,
-            physicalX: 40.0,
-            timeStamp: Duration(milliseconds: 5),
-        ),
-        ui.PointerData(
-            change: ui.PointerChange.remove,
-            physicalX: 40.0,
-            timeStamp: Duration(milliseconds: 6),
-        ),
-      ],
-    );
-
-    final List<PointerEvent> pointerRouterEvents = <PointerEvent>[];
-    GestureBinding.instance.pointerRouter.addGlobalRoute(pointerRouterEvents.add);
-
-    final List<PointerEvent> events = <PointerEvent>[];
-    _binding.callback = events.add;
-
-    GestureBinding.instance.resamplingEnabled = true;
-    GestureBinding.instance.samplingOffset = const Duration(microseconds: -5500);
-
-    ui.window.onPointerDataPacket(packet);
-
-    // No pointer events should have been dispatched yet.
-    expect(events.length, 0);
-
-    // Frame callback should have been requested.
-    FrameCallback callback = _binding.frameCallback;
-    _binding.frameCallback = null;
-    expect(callback, isNotNull);
-
-    _binding.frameTime = const Duration(milliseconds: 7);
-    callback(Duration.zero);
-
-    // One pointer event should have been dispatched.
-    expect(events.length, 1);
-    expect(events[0].runtimeType, equals(PointerDownEvent));
-    expect(events[0].timeStamp, _binding.frameTime + GestureBinding.instance.samplingOffset);
-    expect(events[0].position, Offset(5.0 / ui.window.devicePixelRatio, 0.0));
-
-    // Second frame callback should have been requested.
-    callback = _binding.frameCallback;
-    _binding.frameCallback = null;
-    expect(callback, isNotNull);
-
-    _binding.frameTime = const Duration(milliseconds: 9);
-    callback(Duration.zero);
-
-    // Second pointer event should have been dispatched.
-    expect(events.length, 2);
-    expect(events[1].timeStamp, _binding.frameTime + GestureBinding.instance.samplingOffset);
-    expect(events[1].runtimeType, equals(PointerMoveEvent));
-    expect(events[1].position, Offset(25.0 / ui.window.devicePixelRatio, 0.0));
-    expect(events[1].delta, Offset(20.0 / ui.window.devicePixelRatio, 0.0));
-
-    // Third frame callback should have been requested.
-    callback = _binding.frameCallback;
-    _binding.frameCallback = null;
-    expect(callback, isNotNull);
-
-    _binding.frameTime = const Duration(milliseconds: 11);
-    callback(Duration.zero);
-
-    // Third pointer event should have been dispatched.
-    expect(events.length, 3);
-    expect(events[2].timeStamp, _binding.frameTime + GestureBinding.instance.samplingOffset);
-    expect(events[2].runtimeType, equals(PointerUpEvent));
-    expect(events[2].position, Offset(40.0 / ui.window.devicePixelRatio, 0.0));
-
-    // No frame callback should have been requested.
-    callback = _binding.frameCallback;
-    expect(callback, isNull);
-  });
 }