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Handle a TabBarView special case: last tab deleted before animation ends (#24892)

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Hans Muller 2018-12-11 14:22:27 -08:00 committed by GitHub
parent 3cca1a2ec3
commit 234855ca3d
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2 changed files with 54 additions and 2 deletions
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1
packages/flutter/lib/src/material/tabs.dart
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@ -1170,6 +1170,7 @@ class _TabBarViewState extends State<TabBarView> {
_controller.index = _pageController.page.floor();
_currentIndex = _controller.index;
}
if (_controller.length > 1)
_controller.offset = (_pageController.page - _controller.index).clamp(-1.0, 1.0);
} else if (notification is ScrollEndNotification) {
_controller.index = _pageController.page.round();

51
packages/flutter/test/material/tabs_test.dart
View File

@ -1895,4 +1895,55 @@ void main() {
expect(find.text(AlwaysKeepAliveWidget.text, skipOffstage: false), findsOneWidget);
expect(find.text('4'), findsOneWidget);
});
testWidgets('Removing the last tab', (WidgetTester tester) async {
// This is a regression test for https://github.com/flutter/flutter/issues/24424
final List<Tab> tabs = <Tab>[const Tab(text: 'LEFT'), const Tab(text: 'RIGHT')];
Widget buildFrame(TabController controller) {
return boilerplate(
child: Container(
alignment: Alignment.topLeft,
child: Column(
children: <Widget>[
TabBar(controller: controller, tabs: tabs),
Expanded(child: TabBarView(controller: controller, children: tabs)),
]
),
),
);
}
final TabController controller1 = TabController(
vsync: const TestVSync(),
length: 2,
initialIndex: 0,
);
await tester.pumpWidget(buildFrame(controller1));
expect(controller1.index, 0);
await tester.tap(find.text('RIGHT'));
expect(controller1.index, 1);
expect(controller1.indexIsChanging, true);
// At this point the change selected tab animation hasn't completed.
// When the controller is replaced the TabBarView will see one last
// scroll notification. Since there's only one tab left, it can be
// ignored.
final TabController controller2 = TabController(
vsync: const TestVSync(),
length: 1,
initialIndex: 0,
);
tabs.removeAt(1);
await tester.pumpWidget(buildFrame(controller2));
await tester.pumpAndSettle();
expect(controller1.indexIsChanging, false);
expect(controller2.index, 0);
});
}