tab_scaffold_test.dart 44.9 KB
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// Copyright 2014 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/cupertino.dart';
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import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';
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import 'package:flutter_test/flutter_test.dart';

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import '../image_data.dart';
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import '../rendering/rendering_tester.dart' show TestCallbackPainter;
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import '../widgets/navigator_utils.dart';
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late List<int> selectedTabs;
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class MockCupertinoTabController extends CupertinoTabController {
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  MockCupertinoTabController({ required super.initialIndex });
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  bool isDisposed = false;
  int numOfListeners = 0;

  @override
  void addListener(VoidCallback listener) {
    numOfListeners++;
    super.addListener(listener);
  }

  @override
  void removeListener(VoidCallback listener) {
    numOfListeners--;
    super.removeListener(listener);
  }

  @override
  void dispose() {
    isDisposed = true;
    super.dispose();
  }
}

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void main() {
  setUp(() {
    selectedTabs = <int>[];
  });

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  BottomNavigationBarItem tabGenerator(int index) {
    return BottomNavigationBarItem(
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      icon: ImageIcon(MemoryImage(Uint8List.fromList(kTransparentImage))),
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      label: 'Tab ${index + 1}',
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    );
  }

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  testWidgets('Tab switching', (WidgetTester tester) async {
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    final List<int> tabsPainted = <int>[];

    await tester.pumpWidget(
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      CupertinoApp(
        home: CupertinoTabScaffold(
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          tabBar: _buildTabBar(),
          tabBuilder: (BuildContext context, int index) {
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            return CustomPaint(
              painter: TestCallbackPainter(
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                onPaint: () { tabsPainted.add(index); },
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              ),
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              child: Text('Page ${index + 1}'),
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            );
          },
        ),
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      ),
    );

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    expect(tabsPainted, const <int>[0]);
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    RichText tab1 = tester.widget(find.descendant(
      of: find.text('Tab 1'),
      matching: find.byType(RichText),
    ));
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    expect(tab1.text.style!.color, CupertinoColors.activeBlue);
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    RichText tab2 = tester.widget(find.descendant(
      of: find.text('Tab 2'),
      matching: find.byType(RichText),
    ));
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    expect(tab2.text.style!.color!.value, 0xFF999999);
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    await tester.tap(find.text('Tab 2'));
    await tester.pump();

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    expect(tabsPainted, const <int>[0, 1]);
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    tab1 = tester.widget(find.descendant(
      of: find.text('Tab 1'),
      matching: find.byType(RichText),
    ));
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    expect(tab1.text.style!.color!.value, 0xFF999999);
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    tab2 = tester.widget(find.descendant(
      of: find.text('Tab 2'),
      matching: find.byType(RichText),
    ));
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    expect(tab2.text.style!.color, CupertinoColors.activeBlue);
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    await tester.tap(find.text('Tab 1'));
    await tester.pump();

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    expect(tabsPainted, const <int>[0, 1, 0]);
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    // CupertinoTabBar's onTap callbacks are passed on.
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    expect(selectedTabs, const <int>[1, 0]);
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  });

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  testWidgets('Tabs are lazy built and moved offstage when inactive', (WidgetTester tester) async {
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    final List<int> tabsBuilt = <int>[];

    await tester.pumpWidget(
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      CupertinoApp(
        home: CupertinoTabScaffold(
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          tabBar: _buildTabBar(),
          tabBuilder: (BuildContext context, int index) {
            tabsBuilt.add(index);
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            return Text('Page ${index + 1}');
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          },
        ),
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      ),
    );

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    expect(tabsBuilt, const <int>[0]);
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    expect(find.text('Page 1'), findsOneWidget);
    expect(find.text('Page 2'), findsNothing);

    await tester.tap(find.text('Tab 2'));
    await tester.pump();

    // Both tabs are built but only one is onstage.
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    expect(tabsBuilt, const <int>[0, 0, 1]);
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    expect(find.text('Page 1', skipOffstage: false), isOffstage);
    expect(find.text('Page 2'), findsOneWidget);

    await tester.tap(find.text('Tab 1'));
    await tester.pump();

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    expect(tabsBuilt, const <int>[0, 0, 1, 0, 1]);
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    expect(find.text('Page 1'), findsOneWidget);
    expect(find.text('Page 2', skipOffstage: false), isOffstage);
  });
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  testWidgets('Last tab gets focus', (WidgetTester tester) async {
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    // 2 nodes for 2 tabs
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    final List<FocusNode> focusNodes = <FocusNode>[
      FocusNode(debugLabel: 'Node 1'),
      FocusNode(debugLabel: 'Node 2'),
    ];
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    for (final FocusNode focusNode in focusNodes) {
      addTearDown(focusNode.dispose);
    }
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    await tester.pumpWidget(
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      CupertinoApp(
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        home: CupertinoTabScaffold(
          tabBar: _buildTabBar(),
          tabBuilder: (BuildContext context, int index) {
            return CupertinoTextField(
              focusNode: focusNodes[index],
              autofocus: true,
            );
          },
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        ),
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      ),
    );

    expect(focusNodes[0].hasFocus, isTrue);

    await tester.tap(find.text('Tab 2'));
    await tester.pump();

    expect(focusNodes[0].hasFocus, isFalse);
    expect(focusNodes[1].hasFocus, isTrue);

    await tester.tap(find.text('Tab 1'));
    await tester.pump();

    expect(focusNodes[0].hasFocus, isTrue);
    expect(focusNodes[1].hasFocus, isFalse);
  });

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  testWidgets('Do not affect focus order in the route', (WidgetTester tester) async {
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    final List<FocusNode> focusNodes = <FocusNode>[
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      FocusNode(debugLabel: 'Node 1'),
      FocusNode(debugLabel: 'Node 2'),
      FocusNode(debugLabel: 'Node 3'),
      FocusNode(debugLabel: 'Node 4'),
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    ];
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    for (final FocusNode focusNode in focusNodes) {
      addTearDown(focusNode.dispose);
    }
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    await tester.pumpWidget(
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      CupertinoApp(
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        home: CupertinoTabScaffold(
          tabBar: _buildTabBar(),
          tabBuilder: (BuildContext context, int index) {
            return Column(
              children: <Widget>[
                CupertinoTextField(
                  focusNode: focusNodes[index * 2],
                  placeholder: 'TextField 1',
                ),
                CupertinoTextField(
                  focusNode: focusNodes[index * 2 + 1],
                  placeholder: 'TextField 2',
                ),
              ],
            );
          },
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        ),
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      ),
    );

    expect(
      focusNodes.any((FocusNode node) => node.hasFocus),
      isFalse,
    );

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    await tester.tap(find.widgetWithText(CupertinoTextField, 'TextField 2'));
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    expect(
      focusNodes.indexOf(focusNodes.singleWhere((FocusNode node) => node.hasFocus)),
      1,
    );

    await tester.tap(find.text('Tab 2'));
    await tester.pump();

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    await tester.tap(find.widgetWithText(CupertinoTextField, 'TextField 1'));
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    expect(
      focusNodes.indexOf(focusNodes.singleWhere((FocusNode node) => node.hasFocus)),
      2,
    );

    await tester.tap(find.text('Tab 1'));
    await tester.pump();

    // Upon going back to tab 1, the item it tab 1 that previously had the focus
    // (TextField 2) gets it back.
    expect(
      focusNodes.indexOf(focusNodes.singleWhere((FocusNode node) => node.hasFocus)),
      1,
    );
  });
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  testWidgets('Programmatic tab switching by changing the index of an existing controller', (WidgetTester tester) async {
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    final CupertinoTabController controller = CupertinoTabController(initialIndex: 1);
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    addTearDown(controller.dispose);
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    final List<int> tabsPainted = <int>[];

    await tester.pumpWidget(
      CupertinoApp(
        home: CupertinoTabScaffold(
          tabBar: _buildTabBar(),
          controller: controller,
          tabBuilder: (BuildContext context, int index) {
            return CustomPaint(
              painter: TestCallbackPainter(
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                onPaint: () { tabsPainted.add(index); },
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              ),
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              child: Text('Page ${index + 1}'),
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            );
          },
        ),
      ),
    );

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    expect(tabsPainted, const <int>[1]);
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    controller.index = 0;
    await tester.pump();

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    expect(tabsPainted, const <int>[1, 0]);
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    // onTap is not called when changing tabs programmatically.
    expect(selectedTabs, isEmpty);

    // Can still tap out of the programmatically selected tab.
    await tester.tap(find.text('Tab 2'));
    await tester.pump();

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    expect(tabsPainted, const <int>[1, 0, 1]);
    expect(selectedTabs, const <int>[1]);
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  });

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  testWidgets('Programmatic tab switching by passing in a new controller', (WidgetTester tester) async {
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    final List<int> tabsPainted = <int>[];

    await tester.pumpWidget(
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      CupertinoApp(
        home: CupertinoTabScaffold(
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          tabBar: _buildTabBar(),
          tabBuilder: (BuildContext context, int index) {
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            return CustomPaint(
              painter: TestCallbackPainter(
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                onPaint: () { tabsPainted.add(index); },
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              ),
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              child: Text('Page ${index + 1}'),
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            );
          },
        ),
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      ),
    );

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    expect(tabsPainted, const <int>[0]);
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    final CupertinoTabController controller = CupertinoTabController(initialIndex: 1);
    addTearDown(controller.dispose);
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    await tester.pumpWidget(
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      CupertinoApp(
        home: CupertinoTabScaffold(
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          tabBar: _buildTabBar(),
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          controller: controller, // Programmatically change the tab now.
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          tabBuilder: (BuildContext context, int index) {
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            return CustomPaint(
              painter: TestCallbackPainter(
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                onPaint: () { tabsPainted.add(index); },
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              ),
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              child: Text('Page ${index + 1}'),
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            );
          },
        ),
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      ),
    );

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    expect(tabsPainted, const <int>[0, 1]);
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    // onTap is not called when changing tabs programmatically.
    expect(selectedTabs, isEmpty);

    // Can still tap out of the programmatically selected tab.
    await tester.tap(find.text('Tab 1'));
    await tester.pump();

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    expect(tabsPainted, const <int>[0, 1, 0]);
    expect(selectedTabs, const <int>[0]);
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  });
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  testWidgets('Tab bar respects themes', (WidgetTester tester) async {
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    await tester.pumpWidget(
      CupertinoApp(
        home: CupertinoTabScaffold(
          tabBar: _buildTabBar(),
          tabBuilder: (BuildContext context, int index) {
            return const Placeholder();
          },
        ),
      ),
    );

    BoxDecoration tabDecoration = tester.widget<DecoratedBox>(find.descendant(
      of: find.byType(CupertinoTabBar),
      matching: find.byType(DecoratedBox),
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    )).decoration as BoxDecoration;
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    expect(tabDecoration.color, isSameColorAs(const Color(0xF0F9F9F9))); // Inherited from theme.
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    await tester.tap(find.text('Tab 2'));
    await tester.pump();

    // Pump again but with dark theme.
    await tester.pumpWidget(
      CupertinoApp(
        theme: const CupertinoThemeData(
          brightness: Brightness.dark,
          primaryColor: CupertinoColors.destructiveRed,
        ),
        home: CupertinoTabScaffold(
          tabBar: _buildTabBar(),
          tabBuilder: (BuildContext context, int index) {
            return const Placeholder();
          },
        ),
      ),
    );

    tabDecoration = tester.widget<DecoratedBox>(find.descendant(
      of: find.byType(CupertinoTabBar),
      matching: find.byType(DecoratedBox),
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    )).decoration as BoxDecoration;
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    expect(tabDecoration.color, isSameColorAs(const Color(0xF01D1D1D)));
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    final RichText tab1 = tester.widget(find.descendant(
      of: find.text('Tab 1'),
      matching: find.byType(RichText),
    ));
    // Tab 2 should still be selected after changing theme.
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    expect(tab1.text.style!.color!.value, 0xFF757575);
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    final RichText tab2 = tester.widget(find.descendant(
      of: find.text('Tab 2'),
      matching: find.byType(RichText),
    ));
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    expect(tab2.text.style!.color, isSameColorAs(CupertinoColors.systemRed.darkColor));
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  });
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  testWidgets('Tab contents are padded when there are view insets', (WidgetTester tester) async {
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    late BuildContext innerContext;
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    await tester.pumpWidget(
      CupertinoApp(
        home: MediaQuery(
          data: const MediaQueryData(
            viewInsets: EdgeInsets.only(bottom: 200),
          ),
          child: CupertinoTabScaffold(
            tabBar: _buildTabBar(),
            tabBuilder: (BuildContext context, int index) {
              innerContext = context;
              return const Placeholder();
            },
          ),
        ),
      ),
    );

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    expect(tester.getRect(find.byType(Placeholder)), const Rect.fromLTWH(0, 0, 800, 400));
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    // Don't generate more media query padding from the translucent bottom
    // tab since the tab is behind the keyboard now.
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    expect(MediaQuery.of(innerContext).padding.bottom, 0);
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  });

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  testWidgets('Tab contents are not inset when resizeToAvoidBottomInset overridden', (WidgetTester tester) async {
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    late BuildContext innerContext;
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    await tester.pumpWidget(
      CupertinoApp(
        home: MediaQuery(
          data: const MediaQueryData(
            viewInsets: EdgeInsets.only(bottom: 200),
          ),
          child: CupertinoTabScaffold(
            resizeToAvoidBottomInset: false,
            tabBar: _buildTabBar(),
            tabBuilder: (BuildContext context, int index) {
              innerContext = context;
              return const Placeholder();
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            },
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          ),
        ),
      ),
    );

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    expect(tester.getRect(find.byType(Placeholder)), const Rect.fromLTWH(0, 0, 800, 600));
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    // Media query padding shows up in the inner content because it wasn't masked
    // by the view inset.
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    expect(MediaQuery.of(innerContext).padding.bottom, 50);
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  });

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  testWidgets('Tab contents bottom padding are not consumed by viewInsets when resizeToAvoidBottomInset overridden', (WidgetTester tester) async {
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    final Widget child = Localizations(
      locale: const Locale('en', 'US'),
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      delegates: const <LocalizationsDelegate<dynamic>>[
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        DefaultWidgetsLocalizations.delegate,
        DefaultCupertinoLocalizations.delegate,
      ],
      child: Directionality(
        textDirection: TextDirection.ltr,
        child: CupertinoTabScaffold(
          resizeToAvoidBottomInset: false,
          tabBar: _buildTabBar(),
          tabBuilder: (BuildContext context, int index) {
            return const Placeholder();
          },
        ),
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      ),
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    );

    await tester.pumpWidget(
      CupertinoApp(
        home: MediaQuery(
          data: const MediaQueryData(
            viewInsets: EdgeInsets.only(bottom: 20.0),
          ),
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          child: child,
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        ),
      ),
    );

    final Offset initialPoint = tester.getCenter(find.byType(Placeholder));

    // Consume bottom padding - as if by the keyboard opening
    await tester.pumpWidget(
      MediaQuery(
        data: const MediaQueryData(
          viewPadding: EdgeInsets.only(bottom: 20),
          viewInsets: EdgeInsets.only(bottom: 300),
        ),
        child: child,
      ),
    );

    final Offset finalPoint = tester.getCenter(find.byType(Placeholder));

    expect(initialPoint, finalPoint);
  });

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  testWidgets(
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    'Opaque tab bar consumes bottom padding while non opaque tab bar does not',
    (WidgetTester tester) async {
      // Regression test for https://github.com/flutter/flutter/issues/43581.
      Future<EdgeInsets> getContentPaddingWithTabBarColor(Color color) async {
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        late EdgeInsets contentPadding;
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        await tester.pumpWidget(
          CupertinoApp(
            home: MediaQuery(
              data: const MediaQueryData(padding: EdgeInsets.only(bottom: 50)),
              child: CupertinoTabScaffold(
                tabBar: CupertinoTabBar(
                  backgroundColor: color,
                  items: List<BottomNavigationBarItem>.generate(2, tabGenerator),
                ),
                tabBuilder: (BuildContext context, int index) {
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                  contentPadding = MediaQuery.paddingOf(context);
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                  return const Placeholder();
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                },
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              ),
            ),
          ),
        );
        return contentPadding;
      }

      expect(await getContentPaddingWithTabBarColor(const Color(0xAAFFFFFF)), isNot(EdgeInsets.zero));
      expect(await getContentPaddingWithTabBarColor(const Color(0xFFFFFFFF)), EdgeInsets.zero);
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    },
  );
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  testWidgets('Tab and page scaffolds do not double stack view insets', (WidgetTester tester) async {
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    late BuildContext innerContext;
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    await tester.pumpWidget(
      CupertinoApp(
        home: MediaQuery(
          data: const MediaQueryData(
            viewInsets: EdgeInsets.only(bottom: 200),
          ),
          child: CupertinoTabScaffold(
            tabBar: _buildTabBar(),
            tabBuilder: (BuildContext context, int index) {
              return CupertinoPageScaffold(
                child: Builder(
                  builder: (BuildContext context) {
                    innerContext = context;
                    return const Placeholder();
                  },
                ),
              );
            },
          ),
        ),
      ),
    );

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    expect(tester.getRect(find.byType(Placeholder)), const Rect.fromLTWH(0, 0, 800, 400));
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    expect(MediaQuery.of(innerContext).padding.bottom, 0);
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  });
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  testWidgets('Deleting tabs after selecting them should switch to the last available tab', (WidgetTester tester) async {
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    final List<int> tabsBuilt = <int>[];

    await tester.pumpWidget(
      CupertinoApp(
        home: CupertinoTabScaffold(
          tabBar: CupertinoTabBar(
            items: List<BottomNavigationBarItem>.generate(4, tabGenerator),
            onTap: (int newTab) => selectedTabs.add(newTab),
          ),
          tabBuilder: (BuildContext context, int index) {
            tabsBuilt.add(index);
            return Text('Page ${index + 1}');
          },
        ),
      ),
    );

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    expect(tabsBuilt, const <int>[0]);
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    // selectedTabs list is appended to on onTap callbacks. We didn't tap
    // any tabs yet.
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    expect(selectedTabs, const <int>[]);
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    tabsBuilt.clear();

    await tester.tap(find.text('Tab 4'));
    await tester.pump();

    // Tabs 1 and 4 are built but only one is onstage.
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    expect(tabsBuilt, const <int>[0, 3]);
    expect(selectedTabs, const <int>[3]);
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    expect(find.text('Page 1', skipOffstage: false), isOffstage);
    expect(find.text('Page 4'), findsOneWidget);
    tabsBuilt.clear();

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    // Delete 2 tabs while Page 4 is still selected.
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    await tester.pumpWidget(
      CupertinoApp(
        home: CupertinoTabScaffold(
          tabBar: CupertinoTabBar(
            items: List<BottomNavigationBarItem>.generate(2, tabGenerator),
            onTap: (int newTab) => selectedTabs.add(newTab),
          ),
          tabBuilder: (BuildContext context, int index) {
            tabsBuilt.add(index);
            // Change the builder too.
            return Text('Different page ${index + 1}');
          },
        ),
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      ),
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    );

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    expect(tabsBuilt, const <int>[0, 1]);
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    // We didn't tap on any additional tabs to invoke the onTap callback. We
    // just deleted a tab.
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    expect(selectedTabs, const <int>[3]);
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    // Tab 1 was previously built so it's rebuilt again, albeit offstage.
    expect(find.text('Different page 1', skipOffstage: false), isOffstage);
    // Since all the tabs after tab 2 are deleted, tab 2 is now the last tab and
    // the actively shown tab.
    expect(find.text('Different page 2'), findsOneWidget);
    // No more tab 4 since it's deleted.
    expect(find.text('Different page 4', skipOffstage: false), findsNothing);
    // We also changed the builder so no tabs should be built with the old
    // builder.
    expect(find.text('Page 1', skipOffstage: false), findsNothing);
    expect(find.text('Page 2', skipOffstage: false), findsNothing);
    expect(find.text('Page 4', skipOffstage: false), findsNothing);
  });
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  // Regression test for https://github.com/flutter/flutter/issues/33455
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  testWidgets('Adding new tabs does not crash the app', (WidgetTester tester) async {
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    final List<int> tabsPainted = <int>[];
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    final CupertinoTabController controller = CupertinoTabController();
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    addTearDown(controller.dispose);
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    await tester.pumpWidget(
      CupertinoApp(
        home: CupertinoTabScaffold(
          tabBar: CupertinoTabBar(
            items: List<BottomNavigationBarItem>.generate(10, tabGenerator),
          ),
          controller: controller,
          tabBuilder: (BuildContext context, int index) {
            return CustomPaint(
              painter: TestCallbackPainter(
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                onPaint: () { tabsPainted.add(index); },
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              ),
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              child: Text('Page ${index + 1}'),
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            );
          },
        ),
      ),
    );

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

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

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

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

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

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  testWidgets(
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    'If a controller is initially provided then the parent stops doing so for rebuilds, '
    'a new instance of CupertinoTabController should be created and used by the widget, '
    "while preserving the previous controller's tab index",
688 689
    (WidgetTester tester) async {
      final List<int> tabsPainted = <int>[];
690
      final CupertinoTabController oldController = CupertinoTabController();
691
      addTearDown(oldController.dispose);
692 693 694 695 696 697 698 699 700 701 702

      await tester.pumpWidget(
        CupertinoApp(
          home: CupertinoTabScaffold(
            tabBar: CupertinoTabBar(
              items: List<BottomNavigationBarItem>.generate(10, tabGenerator),
            ),
            controller: oldController,
            tabBuilder: (BuildContext context, int index) {
              return CustomPaint(
                painter: TestCallbackPainter(
703
                  onPaint: () { tabsPainted.add(index); },
704
                ),
705
                child: Text('Page ${index + 1}'),
706
              );
707
            },
708
          ),
709
        ),
710 711
      );

712
      expect(tabsPainted, const <int> [0]);
713 714 715 716 717 718 719 720 721 722 723

      await tester.pumpWidget(
        CupertinoApp(
          home: CupertinoTabScaffold(
            tabBar: CupertinoTabBar(
              items: List<BottomNavigationBarItem>.generate(10, tabGenerator),
            ),
            tabBuilder:
            (BuildContext context, int index) {
              return CustomPaint(
                painter: TestCallbackPainter(
724
                  onPaint: () { tabsPainted.add(index); },
725
                ),
726
                child: Text('Page ${index + 1}'),
727
              );
728
            },
729
          ),
730
        ),
731 732
      );

733
      expect(tabsPainted, const <int> [0, 0]);
734 735 736 737 738

      await tester.tap(find.text('Tab 2'));
      await tester.pump();

      // Tapping the tabs should still work.
739
      expect(tabsPainted, const <int>[0, 0, 1]);
740 741 742 743 744

      oldController.index = 10;
      await tester.pump();

      // Changing [index] of the oldController should not work.
745
      expect(tabsPainted, const <int> [0, 0, 1]);
746 747
    },
  );
748

749
  testWidgets(
750 751
    'Do not call dispose on a controller that we do not own '
    'but do remove from its listeners when done listening to it',
752 753
    (WidgetTester tester) async {
      final MockCupertinoTabController mockController = MockCupertinoTabController(initialIndex: 0);
754
      addTearDown(mockController.dispose);
755 756 757 758 759 760 761 762 763 764

      await tester.pumpWidget(
        CupertinoApp(
          home: CupertinoTabScaffold(
            tabBar: CupertinoTabBar(
              items: List<BottomNavigationBarItem>.generate(2, tabGenerator),
            ),
            controller: mockController,
            tabBuilder: (BuildContext context, int index) => const Placeholder(),
          ),
765
        ),
766 767 768 769 770 771 772 773 774 775 776 777 778
      );

      expect(mockController.numOfListeners, 1);
      expect(mockController.isDisposed, isFalse);

      await tester.pumpWidget(
        CupertinoApp(
          home: CupertinoTabScaffold(
            tabBar: CupertinoTabBar(
              items: List<BottomNavigationBarItem>.generate(2, tabGenerator),
            ),
            tabBuilder: (BuildContext context, int index) => const Placeholder(),
          ),
779
        ),
780 781 782 783
      );

      expect(mockController.numOfListeners, 0);
      expect(mockController.isDisposed, isFalse);
784 785
    },
  );
786

787
  testWidgets('The owner can dispose the old controller', (WidgetTester tester) async {
788 789 790 791 792 793 794 795 796
    CupertinoTabController controller = CupertinoTabController(initialIndex: 2);

    await tester.pumpWidget(
      CupertinoApp(
        home: CupertinoTabScaffold(
          tabBar: CupertinoTabBar(
            items: List<BottomNavigationBarItem>.generate(3, tabGenerator),
          ),
          controller: controller,
797
          tabBuilder: (BuildContext context, int index) => const Placeholder(),
798
        ),
799
      ),
800 801 802 803 804 805
    );
    expect(find.text('Tab 1'), findsOneWidget);
    expect(find.text('Tab 2'), findsOneWidget);
    expect(find.text('Tab 3'), findsOneWidget);

    controller.dispose();
806
    controller = CupertinoTabController();
807
    addTearDown(controller.dispose);
808 809 810 811 812 813 814
    await tester.pumpWidget(
      CupertinoApp(
        home: CupertinoTabScaffold(
          tabBar: CupertinoTabBar(
            items: List<BottomNavigationBarItem>.generate(2, tabGenerator),
          ),
          controller: controller,
815
          tabBuilder: (BuildContext context, int index) => const Placeholder(),
816
        ),
817
      ),
818 819 820 821 822 823 824 825
    );

    // Should not crash here.
    expect(find.text('Tab 1'), findsOneWidget);
    expect(find.text('Tab 2'), findsOneWidget);
    expect(find.text('Tab 3'), findsNothing);
  });

826
  testWidgets('A controller can control more than one CupertinoTabScaffold, '
827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845
    'removal of listeners does not break the controller',
    (WidgetTester tester) async {
      final List<int> tabsPainted0 = <int>[];
      final List<int> tabsPainted1 = <int>[];
      MockCupertinoTabController controller = MockCupertinoTabController(initialIndex: 2);

      await tester.pumpWidget(
        CupertinoApp(
          home: CupertinoPageScaffold(
            child: Stack(
              children: <Widget>[
                CupertinoTabScaffold(
                  tabBar: CupertinoTabBar(
                    items: List<BottomNavigationBarItem>.generate(3, tabGenerator),
                  ),
                  controller: controller,
                  tabBuilder: (BuildContext context, int index) {
                    return CustomPaint(
                      painter: TestCallbackPainter(
846
                        onPaint: () => tabsPainted0.add(index),
847
                      ),
848
                    );
849
                  },
850 851 852 853 854 855 856 857 858
                ),
                CupertinoTabScaffold(
                  tabBar: CupertinoTabBar(
                    items: List<BottomNavigationBarItem>.generate(3, tabGenerator),
                  ),
                  controller: controller,
                  tabBuilder: (BuildContext context, int index) {
                    return CustomPaint(
                      painter: TestCallbackPainter(
859
                        onPaint: () => tabsPainted1.add(index),
860
                      ),
861
                    );
862
                  },
863
                ),
864 865 866 867
              ],
            ),
          ),
        ),
868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892
      );
      expect(tabsPainted0, const <int>[2]);
      expect(tabsPainted1, const <int>[2]);
      expect(controller.numOfListeners, 2);

      controller.index = 0;
      await tester.pump();
      expect(tabsPainted0, const <int>[2, 0]);
      expect(tabsPainted1, const <int>[2, 0]);

      controller.index = 1;
      // Removing one of the tabs works.
      await tester.pumpWidget(
        CupertinoApp(
          home: CupertinoPageScaffold(
            child: Stack(
              children: <Widget>[
                CupertinoTabScaffold(
                  tabBar: CupertinoTabBar(
                    items: List<BottomNavigationBarItem>.generate(3, tabGenerator),
                  ),
                  controller: controller,
                  tabBuilder: (BuildContext context, int index) {
                    return CustomPaint(
                      painter: TestCallbackPainter(
893
                        onPaint: () => tabsPainted0.add(index),
894
                      ),
895
                    );
896
                  },
897
                ),
898 899 900 901
              ],
            ),
          ),
        ),
902 903 904 905 906 907 908
      );

      expect(tabsPainted0, const <int>[2, 0, 1]);
      expect(tabsPainted1, const <int>[2, 0]);
      expect(controller.numOfListeners, 1);

      // Replacing controller works.
909
      controller.dispose();
910
      controller = MockCupertinoTabController(initialIndex: 2);
911
      addTearDown(controller.dispose);
912 913 914 915 916 917 918 919 920 921 922 923 924
      await tester.pumpWidget(
        CupertinoApp(
          home: CupertinoPageScaffold(
            child: Stack(
              children: <Widget>[
                CupertinoTabScaffold(
                  tabBar: CupertinoTabBar(
                    items: List<BottomNavigationBarItem>.generate(3, tabGenerator),
                  ),
                  controller: controller,
                  tabBuilder: (BuildContext context, int index) {
                    return CustomPaint(
                      painter: TestCallbackPainter(
925 926
                        onPaint: () => tabsPainted0.add(index),
                      ),
927
                    );
928
                  },
929
                ),
930 931 932 933
              ],
            ),
          ),
        ),
934 935 936 937
      );
      expect(tabsPainted0, const <int>[2, 0, 1, 2]);
      expect(tabsPainted1, const <int>[2, 0]);
      expect(controller.numOfListeners, 1);
938 939
    },
  );
940

941
  testWidgets('Assert when current tab index >= number of tabs', (WidgetTester tester) async {
942
    final CupertinoTabController controller = CupertinoTabController(initialIndex: 2);
943
    addTearDown(controller.dispose);
944 945 946 947 948 949 950 951 952 953 954

    try {
      await tester.pumpWidget(
        CupertinoApp(
          home: CupertinoTabScaffold(
            tabBar: CupertinoTabBar(
              items: List<BottomNavigationBarItem>.generate(2, tabGenerator),
            ),
            controller: controller,
            tabBuilder: (BuildContext context, int index) => Text('Different page ${index + 1}'),
          ),
955
        ),
956 957 958 959 960 961 962 963 964 965 966 967 968 969
      );
    } on AssertionError catch (e) {
      expect(e.toString(), contains('controller.index < tabBar.items.length'));
    }

    await tester.pumpWidget(
      CupertinoApp(
        home: CupertinoTabScaffold(
          tabBar: CupertinoTabBar(
            items: List<BottomNavigationBarItem>.generate(3, tabGenerator),
          ),
          controller: controller,
          tabBuilder: (BuildContext context, int index) => Text('Different page ${index + 1}'),
        ),
970
      ),
971 972 973 974 975 976 977 978 979 980 981 982
    );

    expect(tester.takeException(), null);

    controller.index = 10;
    await tester.pump();

    final String message = tester.takeException().toString();
    expect(message, contains('current index ${controller.index}'));
    expect(message, contains('with 3 tabs'));
  });

983
  testWidgets("Don't replace focus nodes for existing tabs when changing tab count", (WidgetTester tester) async {
984
    final CupertinoTabController controller = CupertinoTabController(initialIndex: 2);
985
    addTearDown(controller.dispose);
986

987 988 989 990 991 992
    final List<FocusScopeNode> scopes = <FocusScopeNode>[];
    for (int i = 0; i < 5; i++) {
      final FocusScopeNode scope = FocusScopeNode();
      addTearDown(scope.dispose);
      scopes.add(scope);
    }
993 994 995 996 997 998 999 1000 1001 1002 1003 1004
    await tester.pumpWidget(
        CupertinoApp(
          home: CupertinoTabScaffold(
            tabBar: CupertinoTabBar(
              items: List<BottomNavigationBarItem>.generate(3, tabGenerator),
            ),
            controller: controller,
            tabBuilder: (BuildContext context, int index) {
              scopes[index] = FocusScope.of(context);
              return Container();
            },
          ),
1005
        ),
1006 1007 1008 1009 1010 1011 1012 1013
    );

    for (int i = 0; i < 3; i++) {
      controller.index = i;
      await tester.pump();
    }
    await tester.pump();

1014
    final List<FocusScopeNode> newScopes = <FocusScopeNode>[];
1015 1016 1017 1018 1019 1020 1021 1022
    await tester.pumpWidget(
        CupertinoApp(
          home: CupertinoTabScaffold(
            tabBar: CupertinoTabBar(
              items: List<BottomNavigationBarItem>.generate(5, tabGenerator),
            ),
            controller: controller,
            tabBuilder: (BuildContext context, int index) {
1023
              newScopes.add(FocusScope.of(context));
1024 1025 1026
              return Container();
            },
          ),
1027
        ),
1028 1029 1030 1031 1032 1033 1034 1035 1036 1037
    );
    for (int i = 0; i < 5; i++) {
      controller.index = i;
      await tester.pump();
    }
    await tester.pump();

    expect(scopes.sublist(0, 3), equals(newScopes.sublist(0, 3)));
  });

1038
  testWidgets('Current tab index cannot go below zero or be null', (WidgetTester tester) async {
1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049
    void expectAssertionError(VoidCallback callback, String errorMessage) {
      try {
        callback();
      } on AssertionError catch (e) {
        expect(e.toString(), contains(errorMessage));
      }
    }

    expectAssertionError(() => CupertinoTabController(initialIndex: -1), '>= 0');

    final CupertinoTabController controller = CupertinoTabController();
1050
    addTearDown(controller.dispose);
1051 1052 1053 1054

    expectAssertionError(() => controller.index = -1, '>= 0');
  });

1055
  testWidgets('Does not lose state when focusing on text input', (WidgetTester tester) async {
1056 1057 1058 1059
    // Regression testing for https://github.com/flutter/flutter/issues/28457.

    await tester.pumpWidget(
      MediaQuery(
1060
        data: const MediaQueryData(),
1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095
        child: CupertinoApp(
          home: CupertinoTabScaffold(
            tabBar: _buildTabBar(),
            tabBuilder: (BuildContext context, int index) {
              return const CupertinoTextField();
            },
          ),
        ),
      ),
    );

    final EditableTextState editableState = tester.state<EditableTextState>(find.byType(EditableText));

    await tester.enterText(find.byType(CupertinoTextField), "don't lose me");

    await tester.pumpWidget(
      MediaQuery(
        data: const MediaQueryData(
          viewInsets:  EdgeInsets.only(bottom: 100),
        ),
        child: CupertinoApp(
          home: CupertinoTabScaffold(
            tabBar: _buildTabBar(),
            tabBuilder: (BuildContext context, int index) {
              return const CupertinoTextField();
            },
          ),
        ),
      ),
    );

    // The exact same state instance is still there.
    expect(tester.state<EditableTextState>(find.byType(EditableText)), editableState);
    expect(find.text("don't lose me"), findsOneWidget);
  });
1096

1097
  testWidgets('textScaleFactor is set to 1.0', (WidgetTester tester) async {
1098 1099 1100
    await tester.pumpWidget(
      CupertinoApp(
        home: Builder(builder: (BuildContext context) {
1101 1102 1103
          return MediaQuery.withClampedTextScaling(
            minScaleFactor: 99,
            maxScaleFactor: 99,
1104 1105 1106 1107
            child: CupertinoTabScaffold(
              tabBar: CupertinoTabBar(
                items: List<BottomNavigationBarItem>.generate(
                  10,
1108
                  (int i) => BottomNavigationBarItem(icon: ImageIcon(MemoryImage(Uint8List.fromList(kTransparentImage))), label: '$i'),
1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133
                ),
              ),
              tabBuilder: (BuildContext context, int index) => const Text('content'),
            ),
          );
        }),
      ),
    );

    final Iterable<RichText> barItems = tester.widgetList<RichText>(
      find.descendant(
        of: find.byType(CupertinoTabBar),
        matching: find.byType(RichText),
      ),
    );

    final Iterable<RichText> contents = tester.widgetList<RichText>(
      find.descendant(
        of: find.text('content'),
        matching: find.byType(RichText),
        skipOffstage: false,
      ),
    );

    expect(barItems.length, greaterThan(0));
1134
    expect(barItems, isNot(contains(predicate((RichText t) => t.textScaler != TextScaler.noScaling))));
1135 1136

    expect(contents.length, greaterThan(0));
1137
    expect(contents, isNot(contains(predicate((RichText t) => t.textScaler != const TextScaler.linear(99.0)))));
1138
  });
1139

1140
  testWidgets('state restoration', (WidgetTester tester) async {
1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194
    await tester.pumpWidget(
      CupertinoApp(
        restorationScopeId: 'app',
        home: CupertinoTabScaffold(
          restorationId: 'scaffold',
          tabBar: CupertinoTabBar(
            items: List<BottomNavigationBarItem>.generate(
              4,
              (int i) => BottomNavigationBarItem(icon: const Icon(CupertinoIcons.map), label: 'Tab $i'),
            ),
          ),
          tabBuilder: (BuildContext context, int i) => Text('Content $i'),
        ),
      ),
    );

    expect(find.text('Content 0'), findsOneWidget);
    expect(find.text('Content 1'), findsNothing);
    expect(find.text('Content 2'), findsNothing);
    expect(find.text('Content 3'), findsNothing);

    await tester.tap(find.text('Tab 2'));
    await tester.pumpAndSettle();

    expect(find.text('Content 0'), findsNothing);
    expect(find.text('Content 1'), findsNothing);
    expect(find.text('Content 2'), findsOneWidget);
    expect(find.text('Content 3'), findsNothing);

    await tester.restartAndRestore();

    expect(find.text('Content 0'), findsNothing);
    expect(find.text('Content 1'), findsNothing);
    expect(find.text('Content 2'), findsOneWidget);
    expect(find.text('Content 3'), findsNothing);

    final TestRestorationData data = await tester.getRestorationData();

    await tester.tap(find.text('Tab 1'));
    await tester.pumpAndSettle();

    expect(find.text('Content 0'), findsNothing);
    expect(find.text('Content 1'), findsOneWidget);
    expect(find.text('Content 2'), findsNothing);
    expect(find.text('Content 3'), findsNothing);

    await tester.restoreFrom(data);

    expect(find.text('Content 0'), findsNothing);
    expect(find.text('Content 1'), findsNothing);
    expect(find.text('Content 2'), findsOneWidget);
    expect(find.text('Content 3'), findsNothing);
  });

1195
  testWidgets('switch from internal to external controller with state restoration', (WidgetTester tester) async {
1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228
    Widget buildWidget({CupertinoTabController? controller}) {
      return CupertinoApp(
        restorationScopeId: 'app',
        home: CupertinoTabScaffold(
          controller: controller,
          restorationId: 'scaffold',
          tabBar: CupertinoTabBar(
            items: List<BottomNavigationBarItem>.generate(
              4,
              (int i) => BottomNavigationBarItem(icon: const Icon(CupertinoIcons.map), label: 'Tab $i'),
            ),
          ),
          tabBuilder: (BuildContext context, int i) => Text('Content $i'),
        ),
      );
    }

    await tester.pumpWidget(buildWidget());

    expect(find.text('Content 0'), findsOneWidget);
    expect(find.text('Content 1'), findsNothing);
    expect(find.text('Content 2'), findsNothing);
    expect(find.text('Content 3'), findsNothing);

    await tester.tap(find.text('Tab 2'));
    await tester.pumpAndSettle();

    expect(find.text('Content 0'), findsNothing);
    expect(find.text('Content 1'), findsNothing);
    expect(find.text('Content 2'), findsOneWidget);
    expect(find.text('Content 3'), findsNothing);

    final CupertinoTabController controller = CupertinoTabController(initialIndex: 3);
1229
    addTearDown(controller.dispose);
1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243
    await tester.pumpWidget(buildWidget(controller: controller));

    expect(find.text('Content 0'), findsNothing);
    expect(find.text('Content 1'), findsNothing);
    expect(find.text('Content 2'), findsNothing);
    expect(find.text('Content 3'), findsOneWidget);

    await tester.pumpWidget(buildWidget());

    expect(find.text('Content 0'), findsOneWidget);
    expect(find.text('Content 1'), findsNothing);
    expect(find.text('Content 2'), findsNothing);
    expect(find.text('Content 3'), findsNothing);
  });
1244 1245 1246

  group('Android Predictive Back', () {
    bool? lastFrameworkHandlesBack;
1247
    setUp(() async {
1248 1249 1250 1251 1252 1253 1254 1255 1256
      lastFrameworkHandlesBack = null;
      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
        .setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
          if (methodCall.method == 'SystemNavigator.setFrameworkHandlesBack') {
            expect(methodCall.arguments, isA<bool>());
            lastFrameworkHandlesBack = methodCall.arguments as bool;
          }
          return;
        });
1257 1258 1259 1260 1261 1262
      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
          .handlePlatformMessage(
            'flutter/lifecycle',
            const StringCodec().encodeMessage(AppLifecycleState.resumed.toString()),
            (ByteData? data) {},
          );
1263 1264 1265 1266 1267 1268 1269
    });

    tearDown(() {
      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
          .setMockMethodCallHandler(SystemChannels.platform, null);
    });

1270
    testWidgets('System back navigation inside of tabs', (WidgetTester tester) async {
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      await tester.pumpWidget(
        CupertinoApp(
          home: MediaQuery(
            data: const MediaQueryData(
              viewInsets: EdgeInsets.only(bottom: 200),
            ),
            child: CupertinoTabScaffold(
              tabBar: _buildTabBar(),
              tabBuilder: (BuildContext context, int index) {
                return CupertinoTabView(
                  builder: (BuildContext context) {
                    return CupertinoPageScaffold(
                      navigationBar: CupertinoNavigationBar(
                        middle: Text('Page 1 of tab ${index + 1}'),
                      ),
                      child: Center(
                        child: CupertinoButton(
                          child: const Text('Next page'),
                          onPressed: () {
                            Navigator.of(context).push(
                              CupertinoPageRoute<void>(
                                builder: (BuildContext context) {
                                  return CupertinoPageScaffold(
                                    navigationBar: CupertinoNavigationBar(
                                      middle: Text('Page 2 of tab ${index + 1}'),
                                    ),
                                    child: Center(
                                      child: CupertinoButton(
                                        child: const Text('Back'),
                                        onPressed: () {
                                          Navigator.of(context).pop();
                                        },
                                      ),
                                    ),
                                  );
                                },
                              ),
                            );
                          },
                        ),
                      ),
                    );
                  },
                );
              },
            ),
          ),
        ),
      );

      expect(find.text('Page 1 of tab 1'), findsOneWidget);
      expect(find.text('Page 2 of tab 1'), findsNothing);
      expect(lastFrameworkHandlesBack, isFalse);

      await tester.tap(find.text('Next page'));
      await tester.pumpAndSettle();
      expect(find.text('Page 1 of tab 1'), findsNothing);
      expect(find.text('Page 2 of tab 1'), findsOneWidget);
      expect(lastFrameworkHandlesBack, isTrue);

      await simulateSystemBack();
      await tester.pumpAndSettle();
      expect(find.text('Page 1 of tab 1'), findsOneWidget);
      expect(find.text('Page 2 of tab 1'), findsNothing);
      expect(lastFrameworkHandlesBack, isFalse);

      await tester.tap(find.text('Next page'));
      await tester.pumpAndSettle();
      expect(find.text('Page 1 of tab 1'), findsNothing);
      expect(find.text('Page 2 of tab 1'), findsOneWidget);
      expect(lastFrameworkHandlesBack, isTrue);

      await tester.tap(find.text('Tab 2'));
      await tester.pumpAndSettle();
      expect(find.text('Page 1 of tab 2'), findsOneWidget);
      expect(find.text('Page 2 of tab 2'), findsNothing);
      expect(lastFrameworkHandlesBack, isFalse);

      await tester.tap(find.text('Tab 1'));
      await tester.pumpAndSettle();
      expect(find.text('Page 1 of tab 1'), findsNothing);
      expect(find.text('Page 2 of tab 1'), findsOneWidget);
      expect(lastFrameworkHandlesBack, isTrue);

      await simulateSystemBack();
      await tester.pumpAndSettle();
      expect(find.text('Page 1 of tab 1'), findsOneWidget);
      expect(find.text('Page 2 of tab 1'), findsNothing);
      expect(lastFrameworkHandlesBack, isFalse);

      await tester.tap(find.text('Tab 2'));
      await tester.pumpAndSettle();
      expect(find.text('Page 1 of tab 2'), findsOneWidget);
      expect(find.text('Page 2 of tab 2'), findsNothing);
      expect(lastFrameworkHandlesBack, isFalse);
    },
      variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.android }),
      skip: kIsWeb, // [intended] frameworkHandlesBack not used on web.
    );
  });
1371 1372
}

1373
CupertinoTabBar _buildTabBar({ int selectedTab = 0 }) {
1374
  return CupertinoTabBar(
1375
    items: <BottomNavigationBarItem>[
1376
      BottomNavigationBarItem(
1377
        icon: ImageIcon(MemoryImage(Uint8List.fromList(kTransparentImage))),
1378
        label: 'Tab 1',
1379
      ),
1380
      BottomNavigationBarItem(
1381
        icon: ImageIcon(MemoryImage(Uint8List.fromList(kTransparentImage))),
1382
        label: 'Tab 2',
1383 1384
      ),
    ],
1385
    currentIndex: selectedTab,
1386 1387
    onTap: (int newTab) => selectedTabs.add(newTab),
  );
1388
}