anchor.diff:      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.pump(kSlowFeedbackInterval);
         await tester.tapAt(new Point(center.x, center.y + 50.0));
  -      await tester.pump(kSlowFeedbackInteral);
  +      await tester.pump(kSlowFeedbackInterval);
         await tester.tapAt(new Point(center.x, center.y - 50.0));
         await finishPicker(tester);
         expect(hapticFeedbackCount, 3);
  
positive.code:   });
  
    group('haptic feedback', () {
      const Duration kFastFeedbackInteral = const Duration(milliseconds: 10);
      const Duration kSlowFeedbackInteral = const Duration(milliseconds: 200);
      int hapticFeedbackCount;
  
      setUpAll(() {
  
negative.code:     testWidgets('quick successive tap-selects vibrate once', (WidgetTester tester) async {
        Point center = await startPicker(tester, (TimeOfDay time) { });
        await tester.tapAt(new Point(center.x, center.y - 50.0));
        await tester.pump(kFastFeedbackInterval);
        await tester.tapAt(new Point(center.x, center.y + 50.0));
        await finishPicker(tester);
        expect(hapticFeedbackCount, 1);
  