final List<int> tabsPainted = <int>[];
      final CupertinoTabController controller = CupertinoTabController(initialIndex: 0);

      await tester.pumpWidget(
        CupertinoApp(
          home: CupertinoTabScaffold(
            tabBar: CupertinoTabBar(
              items: List<BottomNavigationBarItem>.generate(10, tabGenerator),
            ),
            controller: controller,
            tabBuilder: (BuildContext context, int index) {
              return CustomPaint(
                child: Text('Page ${index + 1}'),
                painter: TestCallbackPainter(
                  onPaint: () { tabsPainted.add(index); }
                ),
              );
            }
          ),
        )
      );

      expect(tabsPainted, <int> [0]);

      await tester.pumpWidget(
        CupertinoApp(
          home: CupertinoTabScaffold(
            tabBar: CupertinoTabBar(
              items: List<BottomNavigationBarItem>.generate(20, tabGenerator),
            ),
            controller: controller,
            tabBuilder:
            (BuildContext context, int index) {
              return CustomPaint(
                child: Text('Page ${index + 1}'),
                painter: TestCallbackPainter(
                  onPaint: () { tabsPainted.add(index); }
                ),
              );
            }
          ),
        )
      );

      expect(tabsPainted, <int> [0, 0]);

      await tester.tap(find.text('Tab 19'));
      await tester.pump();

      // Tapping the tabs should still work.
      expect(tabsPainted, <int>[0, 0, 18]);