anchor.diff:      // Now that the appbar is fully expanded, Perform the same drag
       // scenario in reverse: drag the appbar up and down and then trigger
       // the snap closed animation.
  -    gesture = await tester.startGesture(const Point(50.0, 256.0));
  +    gesture = await tester.startGesture(const Offset(50.0, 256.0));
       await gesture.moveBy(const Offset(0.0, -128.0));
       await tester.pump();
       expect(appBarBottom(tester), kTextTabBarHeight);
  
positive.code: }
  
  double appBarHeight(WidgetTester tester) => tester.getSize(find.byType(AppBar)).height;
  double appBarTop(WidgetTester tester) => tester.getTopLeft(find.byType(AppBar)).y;
  double appBarBottom(WidgetTester tester) => tester.getBottomLeft(find.byType(AppBar)).y;
  
  double tabBarHeight(WidgetTester tester) => tester.getSize(find.byType(TabBar)).height;
  
  
negative.code:     // Now that the app bar is open, perform the same drag scenario
      // in reverse: drag the appbar up and down and then trigger the
      // snap closed animation.
      gesture = await tester.startGesture(const Offset(50.0, 256.0));
      await gesture.moveBy(const Offset(0.0, -128.0)); // drag the appbar closed
      await tester.pump();
      expect(appBarBottom(tester), 0.0);
  