anchor.diff:  
         TestGesture gesture = await tester.startGesture(hour3);
         await gesture.moveBy(hour0 - hour3);
  -      await tester.pump(kFastFeedbackInteral);
  +      await tester.pump(kFastFeedbackInterval);
         await gesture.moveBy(hour3 - hour0);
  -      await tester.pump(kFastFeedbackInteral);
  +      await tester.pump(kFastFeedbackInterval);
         await gesture.moveBy(hour0 - hour3);
         await gesture.up();
         await finishPicker(tester);
  
positive.code:     testWidgets('slow successive tap-selects vibrate once per tap', (WidgetTester tester) async {
        Point center = await startPicker(tester, (TimeOfDay time) { });
        await tester.tapAt(new Point(center.x, center.y - 50.0));
        await tester.pump(kSlowFeedbackInteral);
        await tester.tapAt(new Point(center.x, center.y + 50.0));
        await tester.pump(kSlowFeedbackInteral);
        await tester.tapAt(new Point(center.x, center.y - 50.0));
        await finishPicker(tester);
        expect(hapticFeedbackCount, 3);
  
negative.code: 
        TestGesture gesture = await tester.startGesture(hour3);
        await gesture.moveBy(hour0 - hour3);
        await tester.pump(kSlowFeedbackInterval);
        await gesture.moveBy(hour3 - hour0);
        await tester.pump(kSlowFeedbackInterval);
        await gesture.moveBy(hour0 - hour3);
        await gesture.up();
        await finishPicker(tester);
  