packages/flutter/test/widgets/animated_list_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/src/foundation/diagnostics.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  testWidgets('AnimatedList', (WidgetTester tester) async {
    Widget builder(BuildContext context, int index, Animation<double> animation) {
      return SizedBox(
        height: 100.0,
        child: Center(
          child: Text('item $index'),
        ),
      );
    }
    final GlobalKey<AnimatedListState> listKey = GlobalKey<AnimatedListState>();

    await tester.pumpWidget(
      Directionality(
        textDirection: TextDirection.ltr,
        child: AnimatedList(
          key: listKey,
          initialItemCount: 2,
          itemBuilder: builder,
        ),
      ),
    );

    expect(find.byWidgetPredicate((Widget widget) {
      return widget is SliverAnimatedList
         && widget.initialItemCount == 2
         && widget.itemBuilder == builder;
    }), findsOneWidget);

    listKey.currentState!.insertItem(0);
    await tester.pump();
    expect(find.text('item 2'), findsOneWidget);

    listKey.currentState!.removeItem(
      2,
      (BuildContext context, Animation<double> animation) {
        return const SizedBox(
          height: 100.0,
          child: Center(child: Text('removing item')),
        );
      },
      duration: const Duration(milliseconds: 100),
    );

    await tester.pump();
    expect(find.text('removing item'), findsOneWidget);
    expect(find.text('item 2'), findsNothing);

    await tester.pumpAndSettle();
    expect(find.text('removing item'), findsNothing);
  });

  group('SliverAnimatedList', () {
    testWidgets('initialItemCount', (WidgetTester tester) async {
      final Map<int, Animation<double>> animations = <int, Animation<double>>{};

      await tester.pumpWidget(
        Directionality(
          textDirection: TextDirection.ltr,
          child: CustomScrollView(
            slivers: <Widget>[
              SliverAnimatedList(
                initialItemCount: 2,
                itemBuilder: (BuildContext context, int index, Animation<double> animation) {
                  animations[index] = animation;
                  return SizedBox(
                    height: 100.0,
                    child: Center(
                      child: Text('item $index'),
                    ),
                  );
                },
              ),
            ],
          ),
        ),
      );

      expect(find.text('item 0'), findsOneWidget);
      expect(find.text('item 1'), findsOneWidget);
      expect(animations.containsKey(0), true);
      expect(animations.containsKey(1), true);
      expect(animations[0]!.value, 1.0);
      expect(animations[1]!.value, 1.0);
    });

    testWidgets('insert', (WidgetTester tester) async {
      final GlobalKey<SliverAnimatedListState> listKey = GlobalKey<SliverAnimatedListState>();

      await tester.pumpWidget(
        Directionality(
          textDirection: TextDirection.ltr,
          child: CustomScrollView(
            slivers: <Widget>[
              SliverAnimatedList(
                key: listKey,
                itemBuilder: (BuildContext context, int index, Animation<double> animation) {
                  return SizeTransition(
                    key: ValueKey<int>(index),
                    sizeFactor: animation,
                    child: SizedBox(
                      height: 100.0,
                      child: Center(child: Text('item $index')),
                    ),
                  );
                },
              ),
            ],
          ),
        ),
      );

      double itemHeight(int index) => tester.getSize(find.byKey(ValueKey<int>(index), skipOffstage: false)).height;
      double itemTop(int index) => tester.getTopLeft(find.byKey(ValueKey<int>(index), skipOffstage: false)).dy;
      double itemBottom(int index) => tester.getBottomLeft(find.byKey(ValueKey<int>(index), skipOffstage: false)).dy;

      listKey.currentState!.insertItem(
        0,
        duration: const Duration(milliseconds: 100),
      );
      await tester.pump();

      // Newly inserted item 0's height should animate from 0 to 100
      expect(itemHeight(0), 0.0);
      await tester.pump(const Duration(milliseconds: 50));
      expect(itemHeight(0), 50.0);
      await tester.pump(const Duration(milliseconds: 50));
      expect(itemHeight(0), 100.0);

      // The list now contains one fully expanded item at the top:
      expect(find.text('item 0'), findsOneWidget);
      expect(itemTop(0), 0.0);
      expect(itemBottom(0), 100.0);

      listKey.currentState!.insertItem(
        0,
        duration: const Duration(milliseconds: 100),
      );
      listKey.currentState!.insertItem(
        0,
        duration: const Duration(milliseconds: 100),
      );
      await tester.pump();

      // The height of the newly inserted items at index 0 and 1 should animate
      // from 0 to 100.
      // The height of the original item, now at index 2, should remain 100.
      expect(itemHeight(0), 0.0);
      expect(itemHeight(1), 0.0);
      expect(itemHeight(2), 100.0);
      await tester.pump(const Duration(milliseconds: 50));
      expect(itemHeight(0), 50.0);
      expect(itemHeight(1), 50.0);
      expect(itemHeight(2), 100.0);
      await tester.pump(const Duration(milliseconds: 50));
      expect(itemHeight(0), 100.0);
      expect(itemHeight(1), 100.0);
      expect(itemHeight(2), 100.0);

      // The newly inserted "item 1" and "item 2" appear above "item 0"
      expect(find.text('item 0'), findsOneWidget);
      expect(find.text('item 1'), findsOneWidget);
      expect(find.text('item 2'), findsOneWidget);
      expect(itemTop(0), 0.0);
      expect(itemBottom(0), 100.0);
      expect(itemTop(1), 100.0);
      expect(itemBottom(1), 200.0);
      expect(itemTop(2), 200.0);
      expect(itemBottom(2), 300.0);
    });

    testWidgets('remove', (WidgetTester tester) async {
      final GlobalKey<SliverAnimatedListState> listKey = GlobalKey<SliverAnimatedListState>();
      final List<int> items = <int>[0, 1, 2];

      Widget buildItem(BuildContext context, int item, Animation<double> animation) {
        return SizeTransition(
          key: ValueKey<int>(item),
          sizeFactor: animation,
          child: SizedBox(
            height: 100.0,
            child: Center(
              child: Text('item $item', textDirection: TextDirection.ltr),
            ),
          ),
        );
      }

      await tester.pumpWidget(
        Directionality(
          textDirection: TextDirection.ltr,
          child: CustomScrollView(
            slivers: <Widget>[
              SliverAnimatedList(
                key: listKey,
                initialItemCount: 3,
                itemBuilder: (BuildContext context, int index, Animation<double> animation) {
                  return buildItem(context, items[index], animation);
                },
              ),
            ],
          ),
        ),
      );

      double itemTop(int index) => tester.getTopLeft(find.byKey(ValueKey<int>(index))).dy;
      double itemBottom(int index) => tester.getBottomLeft(find.byKey(ValueKey<int>(index))).dy;

      expect(find.text('item 0'), findsOneWidget);
      expect(find.text('item 1'), findsOneWidget);
      expect(find.text('item 2'), findsOneWidget);

      items.removeAt(0);
      listKey.currentState!.removeItem(
        0,
        (BuildContext context, Animation<double> animation) => buildItem(context, 0, animation),
        duration: const Duration(milliseconds: 100),
      );

      // Items 0, 1, 2 at 0, 100, 200. All heights 100.
      expect(itemTop(0), 0.0);
      expect(itemBottom(0), 100.0);
      expect(itemTop(1), 100.0);
      expect(itemBottom(1), 200.0);
      expect(itemTop(2), 200.0);
      expect(itemBottom(2), 300.0);

      // Newly removed item 0's height should animate from 100 to 0 over 100ms

      // Items 0, 1, 2 at 0, 50, 150. Item 0's height is 50.
      await tester.pump();
      await tester.pump(const Duration(milliseconds: 50));
      expect(itemTop(0), 0.0);
      expect(itemBottom(0), 50.0);
      expect(itemTop(1), 50.0);
      expect(itemBottom(1), 150.0);
      expect(itemTop(2), 150.0);
      expect(itemBottom(2), 250.0);

      // Items 1, 2 at 0, 100.
      await tester.pumpAndSettle();
      expect(itemTop(1), 0.0);
      expect(itemBottom(1), 100.0);
      expect(itemTop(2), 100.0);
      expect(itemBottom(2), 200.0);
    });

    testWidgets('works in combination with other slivers', (WidgetTester tester) async {
      final GlobalKey<SliverAnimatedListState> listKey = GlobalKey<SliverAnimatedListState>();

      await tester.pumpWidget(
        Directionality(
          textDirection: TextDirection.ltr,
          child: CustomScrollView(
            slivers: <Widget>[
              SliverList(
                delegate: SliverChildListDelegate(<Widget>[
                  const SizedBox(height: 100),
                  const SizedBox(height: 100),
                ]),
              ),
              SliverAnimatedList(
                key: listKey,
                initialItemCount: 3,
                itemBuilder: (BuildContext context, int index, Animation<double> animation) {
                  return SizedBox(
                    height: 100,
                    child: Text('item $index'),
                  );
                },
              ),
            ],
          ),
        ),
      );

      expect(tester.getTopLeft(find.text('item 0')).dy, 200);
      expect(tester.getTopLeft(find.text('item 1')).dy, 300);

      listKey.currentState!.insertItem(3);
      await tester.pumpAndSettle();
      expect(tester.getTopLeft(find.text('item 3')).dy, 500);

      listKey.currentState!.removeItem(0,
        (BuildContext context, Animation<double> animation) {
          return SizeTransition(
            sizeFactor: animation,
            key: const ObjectKey('removing'),
            child: const SizedBox(
              height: 100,
              child: Text('removing'),
            ),
          );
        },
        duration: const Duration(seconds: 1),
      );

      await tester.pump();
      expect(find.text('item 3'), findsNothing);

      await tester.pump(const Duration(milliseconds: 500));
      expect(
        tester.getSize(find.byKey(const ObjectKey('removing'))).height,
        50,
      );
      expect(tester.getTopLeft(find.text('item 0')).dy, 250);

      await tester.pumpAndSettle();
      expect(find.text('removing'), findsNothing);
      expect(tester.getTopLeft(find.text('item 0')).dy, 200);
    });
  });

  testWidgets(
    'AnimatedList.of() and maybeOf called with a context that does not contain AnimatedList',
    (WidgetTester tester) async {
      final GlobalKey key = GlobalKey();
      await tester.pumpWidget(Container(key: key));
      late FlutterError error;
      expect(AnimatedList.maybeOf(key.currentContext!), isNull);
      try {
        AnimatedList.of(key.currentContext!);
      } on FlutterError catch (e) {
        error = e;
      }
      expect(error.diagnostics.length, 4);
      expect(error.diagnostics[2].level, DiagnosticLevel.hint);
      expect(
        error.diagnostics[2].toStringDeep(),
        equalsIgnoringHashCodes(
          'This can happen when the context provided is from the same\n'
          'StatefulWidget that built the AnimatedList. Please see the\n'
          'AnimatedList documentation for examples of how to refer to an\n'
          'AnimatedListState object:\n'
          '  https://api.flutter.dev/flutter/widgets/AnimatedListState-class.html\n',
        ),
      );
      expect(error.diagnostics[3], isA<DiagnosticsProperty<Element>>());
      expect(
        error.toStringDeep(),
        equalsIgnoringHashCodes(
          'FlutterError\n'
          '   AnimatedList.of() called with a context that does not contain an\n'
          '   AnimatedList.\n'
          '   No AnimatedList ancestor could be found starting from the context\n'
          '   that was passed to AnimatedList.of().\n'
          '   This can happen when the context provided is from the same\n'
          '   StatefulWidget that built the AnimatedList. Please see the\n'
          '   AnimatedList documentation for examples of how to refer to an\n'
          '   AnimatedListState object:\n'
          '     https://api.flutter.dev/flutter/widgets/AnimatedListState-class.html\n'
          '   The context used was:\n'
          '     Container-[GlobalKey#32cc6]\n',
        ),
      );
    },
  );

  testWidgets('AnimatedList.clipBehavior is forwarded to its inner CustomScrollView', (WidgetTester tester) async {
    const Clip clipBehavior = Clip.none;

    await tester.pumpWidget(
      Directionality(
        textDirection: TextDirection.ltr,
        child: AnimatedList(
          initialItemCount: 2,
          clipBehavior: clipBehavior,
          itemBuilder: (BuildContext context, int index, Animation<double> _) {
            return SizedBox(
              height: 100.0,
              child: Center(
                child: Text('item $index'),
              ),
            );
          },
        ),
      ),
    );

    expect(tester.widget<CustomScrollView>(find.byType(CustomScrollView)).clipBehavior, clipBehavior);
  });
}