flutter_flutter/packages/flutter/test/widgets/custom_scroll_view_test.dart

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

import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  // Regression test for https://github.com/flutter/flutter/issues/96024
  testWidgets('CustomScrollView.center update test 1', (WidgetTester tester) async {
    final Key centerKey = UniqueKey();
    late StateSetter setState;
    var hasKey = false;
    await tester.pumpWidget(
      Directionality(
        textDirection: TextDirection.ltr,
        child: CustomScrollView(
          center: centerKey,
          slivers: <Widget>[
            const SliverToBoxAdapter(key: Key('a'), child: SizedBox(height: 100.0)),
            StatefulBuilder(
              key: centerKey,
              builder: (BuildContext context, StateSetter setter) {
                setState = setter;
                if (hasKey) {
                  return const SliverToBoxAdapter(key: Key('b'), child: SizedBox(height: 100.0));
                } else {
                  return const SliverToBoxAdapter(child: SizedBox(height: 100.0));
                }
              },
            ),
          ],
        ),
      ),
    );
    await tester.pumpAndSettle();

    // Change the center key will trigger the old RenderObject remove and a new
    // RenderObject insert.
    setState(() {
      hasKey = true;
    });

    await tester.pumpAndSettle();

    // Pass without throw.
  });

  testWidgets('CustomScrollView.center update test 2', (WidgetTester tester) async {
    const slivers1 = <Widget>[
      SliverToBoxAdapter(key: Key('a'), child: SizedBox(height: 100.0)),
      SliverToBoxAdapter(key: Key('b'), child: SizedBox(height: 100.0)),
      SliverToBoxAdapter(key: Key('c'), child: SizedBox(height: 100.0)),
    ];

    const slivers2 = <Widget>[
      SliverToBoxAdapter(key: Key('c'), child: SizedBox(height: 100.0)),
      SliverToBoxAdapter(key: Key('d'), child: SizedBox(height: 100.0)),
      SliverToBoxAdapter(key: Key('a'), child: SizedBox(height: 100.0)),
    ];

    Widget buildFrame(List<Widget> slivers, Key center) {
      return Directionality(
        textDirection: TextDirection.ltr,
        child: CustomScrollView(center: center, slivers: slivers),
      );
    }

    await tester.pumpWidget(buildFrame(slivers1, const Key('b')));
    await tester.pumpAndSettle();

    await tester.pumpWidget(buildFrame(slivers2, const Key('d')));
    await tester.pumpAndSettle();

    // Pass without throw.
  });

  testWidgets('CustomScrollView.center', (WidgetTester tester) async {
    await tester.pumpWidget(
      const Directionality(
        textDirection: TextDirection.ltr,
        child: CustomScrollView(
          slivers: <Widget>[
            SliverToBoxAdapter(key: Key('a'), child: SizedBox(height: 100.0)),
            SliverToBoxAdapter(key: Key('b'), child: SizedBox(height: 100.0)),
          ],
          center: Key('a'),
        ),
      ),
    );
    await tester.pumpAndSettle();
    expect(
      tester.getRect(
        find.descendant(of: find.byKey(const Key('a')), matching: find.byType(SizedBox)),
      ),
      const Rect.fromLTRB(0.0, 0.0, 800.0, 100.0),
    );
    expect(
      tester.getRect(
        find.descendant(of: find.byKey(const Key('b')), matching: find.byType(SizedBox)),
      ),
      const Rect.fromLTRB(0.0, 100.0, 800.0, 200.0),
    );
  });

  testWidgets('CustomScrollView.center', (WidgetTester tester) async {
    await tester.pumpWidget(
      const Directionality(
        textDirection: TextDirection.ltr,
        child: CustomScrollView(
          slivers: <Widget>[
            SliverToBoxAdapter(key: Key('a'), child: SizedBox(height: 100.0)),
            SliverToBoxAdapter(key: Key('b'), child: SizedBox(height: 100.0)),
          ],
          center: Key('b'),
        ),
      ),
    );
    await tester.pumpAndSettle();
    expect(
      tester.getRect(
        find.descendant(
          of: find.byKey(const Key('a'), skipOffstage: false),
          matching: find.byType(SizedBox, skipOffstage: false),
        ),
      ),
      const Rect.fromLTRB(0.0, -100.0, 800.0, 0.0),
    );
    expect(
      tester.getRect(
        find.descendant(of: find.byKey(const Key('b')), matching: find.byType(SizedBox)),
      ),
      const Rect.fromLTRB(0.0, 0.0, 800.0, 100.0),
    );
  });

  testWidgets('CustomScrollView.anchor', (WidgetTester tester) async {
    await tester.pumpWidget(
      const Directionality(
        textDirection: TextDirection.ltr,
        child: CustomScrollView(
          slivers: <Widget>[
            SliverToBoxAdapter(key: Key('a'), child: SizedBox(height: 100.0)),
            SliverToBoxAdapter(key: Key('b'), child: SizedBox(height: 100.0)),
          ],
          center: Key('b'),
          anchor: 1.0,
        ),
      ),
    );
    await tester.pumpAndSettle();
    expect(
      tester.getRect(
        find.descendant(of: find.byKey(const Key('a')), matching: find.byType(SizedBox)),
      ),
      const Rect.fromLTRB(0.0, 500.0, 800.0, 600.0),
    );
    expect(
      tester.getRect(
        find.descendant(
          of: find.byKey(const Key('b'), skipOffstage: false),
          matching: find.byType(SizedBox, skipOffstage: false),
        ),
      ),
      const Rect.fromLTRB(0.0, 600.0, 800.0, 700.0),
    );
  });
}