context_test.dart

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

import 'common.dart';

void main() {
  group('context.watch<T?>', () {
    testWidgets('can watch T', (tester) async {
      final notifier = ValueNotifier(0);

      await tester.pumpWidget(
        ChangeNotifierProvider<ValueNotifier<int>>.value(
          value: notifier,
          child: Builder(
            builder: (context) {
              final notifier = context.watch<ValueNotifier<int>?>();

              return Text(
                notifier?.value.toString() ?? '',
                textDirection: TextDirection.ltr,
              );
            },
          ),
        ),
      );

      expect(find.text('0'), findsOneWidget);

      notifier.value++;
      await tester.pump();

      expect(find.text('1'), findsOneWidget);
    });

    testWidgets('can watch T?', (tester) async {
      final notifier = ValueNotifier(0);

      await tester.pumpWidget(
        ChangeNotifierProvider<ValueNotifier<int>?>.value(
          value: notifier,
          child: Builder(
            builder: (context) {
              final notifier = context.watch<ValueNotifier<int>?>();

              return Text(
                notifier?.value.toString() ?? '',
                textDirection: TextDirection.ltr,
              );
            },
          ),
        ),
      );

      expect(find.text('0'), findsOneWidget);

      notifier.value++;
      await tester.pump();

      expect(find.text('1'), findsOneWidget);
    });

    testWidgets('handles provider missing', (tester) async {
      await tester.pumpWidget(
        Builder(
          builder: (context) {
            final notifier = context.watch<ValueNotifier<int>?>();

            return Text(
              notifier?.value.toString() ?? '',
              textDirection: TextDirection.ltr,
            );
          },
        ),
      );

      expect(find.text(''), findsOneWidget);
    });

    testWidgets(
        'supports relocating with GlobalKey from no provider to a provider',
        (tester) async {
      final widget = Builder(
        key: GlobalKey(),
        builder: (context) {
          final notifier = context.watch<ValueNotifier<int>?>();

          return Text(
            notifier?.value.toString() ?? '',
            textDirection: TextDirection.ltr,
          );
        },
      );

      await tester.pumpWidget(widget);

      expect(find.text(''), findsOneWidget);

      final notifier = ValueNotifier(0);
      await tester.pumpWidget(
        ChangeNotifierProvider<ValueNotifier<int>?>.value(
          value: notifier,
          child: widget,
        ),
      );

      expect(find.text('0'), findsOneWidget);

      notifier.value++;
      await tester.pump();

      expect(find.text('1'), findsOneWidget);
    });
  });

  group('context.watch<T>', () {
    testWidgets('can watch T?', (tester) async {
      final notifier = ValueNotifier(0);

      await tester.pumpWidget(
        ChangeNotifierProvider<ValueNotifier<int>?>.value(
          value: notifier,
          child: Builder(
            builder: (context) {
              final notifier = context.watch<ValueNotifier<int>>();

              return Text(
                notifier.value.toString(),
                textDirection: TextDirection.ltr,
              );
            },
          ),
        ),
      );

      expect(find.text('0'), findsOneWidget);

      notifier.value++;
      await tester.pump();

      expect(find.text('1'), findsOneWidget);
    });

    testWidgets('on T? will throw ProvierNullException if the result is null',
        (tester) async {
      Object? err;
      final onError = FlutterError.onError;
      FlutterError.onError = (details) {
        err = details.exception;
      };

      await tester.pumpWidget(
        ChangeNotifierProvider<ValueNotifier<int>?>.value(
          value: null,
          child: Builder(
            builder: (context) {
              final notifier = context.watch<ValueNotifier<int>>();

              return Text(
                notifier.value.toString(),
                textDirection: TextDirection.ltr,
              );
            },
          ),
        ),
      );

      FlutterError.onError = onError;

      expect(err, isA<ProviderNullException>());
    }, skip: !isSoundMode);
  });

  group('context.select<T?>', () {
    testWidgets('can watch T', (tester) async {
      final notifier = ValueNotifier(0);

      await tester.pumpWidget(
        ChangeNotifierProvider<ValueNotifier<int>>.value(
          value: notifier,
          child: Builder(
            builder: (context) {
              final value =
                  context.select<ValueNotifier<int>?, int?>((n) => n?.value);

              return Text(
                value?.toString() ?? '',
                textDirection: TextDirection.ltr,
              );
            },
          ),
        ),
      );

      expect(find.text('0'), findsOneWidget);

      notifier.value++;
      await tester.pump();

      expect(find.text('1'), findsOneWidget);
    });

    testWidgets('can watch T?', (tester) async {
      final notifier = ValueNotifier(0);

      await tester.pumpWidget(
        ChangeNotifierProvider<ValueNotifier<int>?>.value(
          value: notifier,
          child: Builder(
            builder: (context) {
              final value =
                  context.select<ValueNotifier<int>?, int?>((n) => n?.value);

              return Text(
                value?.toString() ?? '',
                textDirection: TextDirection.ltr,
              );
            },
          ),
        ),
      );

      expect(find.text('0'), findsOneWidget);

      notifier.value++;
      await tester.pump();

      expect(find.text('1'), findsOneWidget);
    });

    testWidgets('handles provider missing', (tester) async {
      await tester.pumpWidget(
        Builder(
          builder: (context) {
            final value =
                context.select<ValueNotifier<int>?, int?>((n) => n?.value);

            return Text(
              value?.toString() ?? '',
              textDirection: TextDirection.ltr,
            );
          },
        ),
      );

      expect(find.text(''), findsOneWidget);
    });

    testWidgets(
        'supports relocating with GlobalKey from no provider to a provider',
        (tester) async {
      final widget = Builder(
        key: GlobalKey(),
        builder: (context) {
          final value =
              context.select<ValueNotifier<int>?, int?>((n) => n?.value);

          return Text(
            value?.toString() ?? '',
            textDirection: TextDirection.ltr,
          );
        },
      );

      await tester.pumpWidget(widget);

      expect(find.text(''), findsOneWidget);

      final notifier = ValueNotifier(0);
      await tester.pumpWidget(
        ChangeNotifierProvider<ValueNotifier<int>?>.value(
          value: notifier,
          child: widget,
        ),
      );

      expect(find.text('0'), findsOneWidget);

      notifier.value++;
      await tester.pump();

      expect(find.text('1'), findsOneWidget);
    });
  });

  group('context.select<T>', () {
    testWidgets('can watch T?', (tester) async {
      final notifier = ValueNotifier(0);

      await tester.pumpWidget(
        ChangeNotifierProvider<ValueNotifier<int>?>.value(
          value: notifier,
          child: Builder(
            builder: (context) {
              final value =
                  context.select<ValueNotifier<int>, int>((n) => n.value);

              return Text(
                value.toString(),
                textDirection: TextDirection.ltr,
              );
            },
          ),
        ),
      );

      expect(find.text('0'), findsOneWidget);

      notifier.value++;
      await tester.pump();

      expect(find.text('1'), findsOneWidget);
    });

    testWidgets('can watch T', (tester) async {
      final notifier = ValueNotifier(0);

      await tester.pumpWidget(
        ChangeNotifierProvider<ValueNotifier<int>>.value(
          value: notifier,
          child: Builder(
            builder: (context) {
              final value =
                  context.select<ValueNotifier<int>, int>((n) => n.value);

              return Text(
                value.toString(),
                textDirection: TextDirection.ltr,
              );
            },
          ),
        ),
      );

      expect(find.text('0'), findsOneWidget);

      notifier.value++;
      await tester.pump();

      expect(find.text('1'), findsOneWidget);
    });

    testWidgets('on T? will throw ProvierNullException if the result is null',
        (tester) async {
      Object? err;
      final onError = FlutterError.onError;
      FlutterError.onError = (details) {
        err = details.exception;
      };

      await tester.pumpWidget(
        ChangeNotifierProvider<ValueNotifier<int>?>.value(
          value: null,
          child: Builder(
            builder: (context) {
              final value =
                  context.select<ValueNotifier<int>, int>((n) => n.value);

              return Text(
                value.toString(),
                textDirection: TextDirection.ltr,
              );
            },
          ),
        ),
      );

      FlutterError.onError = onError;

      expect(err, isA<ProviderNullException>());
    });

    testWidgets('on T? will throw ProvierNullException if new value is null',
        (tester) async {
      Object? err;

      final child = Builder(
        builder: (context) {
          final value = context.select<ValueNotifier<int>, int>((n) => n.value);

          return Text(
            value.toString(),
            textDirection: TextDirection.ltr,
          );
        },
      );

      await tester.pumpWidget(
        ChangeNotifierProvider<ValueNotifier<int>?>.value(
          value: ValueNotifier(0),
          child: child,
        ),
      );

      expect(find.text('0'), findsOneWidget);

      final onError = FlutterError.onError;
      FlutterError.onError = (details) {
        err = details.exception;
      };

      await tester.pumpWidget(
        ChangeNotifierProvider<ValueNotifier<int>?>.value(
          value: null,
          child: child,
        ),
      );

      FlutterError.onError = onError;

      expect(err, isA<ProviderNullException>());
    });
  });

  testWidgets('watch in layoutbuilder', (tester) async {
    await tester.pumpWidget(
      Provider(
        create: (_) => 42,
        child: LayoutBuilder(builder: (context, _) {
          return Text(
            context.watch<int>().toString(),
            textDirection: TextDirection.ltr,
          );
        }),
      ),
    );

    expect(find.text('42'), findsOneWidget);
  });

  testWidgets('select in layoutbuilder', (tester) async {
    await tester.pumpWidget(
      Provider(
        create: (_) => 42,
        child: LayoutBuilder(builder: (context, _) {
          return Text(
            context.select((int i) => '$i'),
            textDirection: TextDirection.ltr,
          );
        }),
      ),
    );

    expect(find.text('42'), findsOneWidget);
  });

  testWidgets('cannot select in listView', (tester) async {
    await tester.pumpWidget(
      Directionality(
        textDirection: TextDirection.ltr,
        child: Provider(
          create: (_) => 0,
          child: ListView.builder(
            itemCount: 1,
            itemBuilder: (context, index) {
              return Text(context.select((int v) => '$v'));
            },
          ),
        ),
      ),
    );

    expect(
      tester.takeException(),
      isAssertionError.having(
          (s) => s.message,
          'message',
          contains(
            'Tried to use context.select inside a SliverList/SliderGridView.',
          )),
    );
  });

  testWidgets('watch in listView', (tester) async {
    final notifier = ValueNotifier([0, 0]);

    await tester.pumpWidget(
      Directionality(
        textDirection: TextDirection.ltr,
        child: ChangeNotifierProvider(
          create: (_) => notifier,
          child: ListView.builder(
            itemCount: 2,
            itemBuilder: (context, index) {
              return Text(
                context
                    .watch<ValueNotifier<List<int>>>()
                    .value[index]
                    .toString(),
              );
            },
          ),
        ),
      ),
    );

    expect(find.text('0'), findsNWidgets(2));

    notifier.value = [1, 0];

    await tester.pump();

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

  testWidgets('watch in gridView', (tester) async {
    final notifier = ValueNotifier([0, 0]);

    await tester.pumpWidget(
      Directionality(
        textDirection: TextDirection.ltr,
        child: ChangeNotifierProvider(
          create: (_) => notifier,
          child: GridView.builder(
            gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
              crossAxisCount: 2,
            ),
            itemCount: 2,
            itemBuilder: (context, index) {
              return Text(
                context
                    .watch<ValueNotifier<List<int>>>()
                    .value[index]
                    .toString(),
              );
            },
          ),
        ),
      ),
    );

    expect(find.text('0'), findsNWidgets(2));

    notifier.value = [1, 0];

    await tester.pump();

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

  group('BuildContext', () {
    testWidgets('internal selected value is updated', (tester) async {
      final notifier = ValueNotifier([false, false, false]);

      final callCounts = <int, int>{
        0: 0,
        1: 0,
        2: 0,
      };

      Widget buildIndex(int index) {
        return Builder(builder: (c) {
          callCounts[index] = callCounts[index]! + 1;
          final selected =
              c.select<ValueNotifier<List<bool>>, bool>((notifier) {
            return notifier.value[index];
          });
          return Text('$index $selected');
        });
      }

      await tester.pumpWidget(
        ChangeNotifierProvider(
          create: (_) => notifier,
          child: Directionality(
            textDirection: TextDirection.ltr,
            child: Column(
              children: [
                buildIndex(0),
                buildIndex(1),
                buildIndex(2),
              ],
            ),
          ),
        ),
      );

      expect(find.text('0 false'), findsOneWidget);
      expect(callCounts[0], 1);
      expect(find.text('1 false'), findsOneWidget);
      expect(callCounts[1], 1);
      expect(find.text('2 false'), findsOneWidget);
      expect(callCounts[2], 1);

      notifier.value = [false, true, false];
      await tester.pump();

      expect(find.text('0 false'), findsOneWidget);
      expect(callCounts[0], 1);
      expect(find.text('1 true'), findsOneWidget);
      expect(callCounts[1], 2);
      expect(find.text('2 false'), findsOneWidget);
      expect(callCounts[2], 1);

      notifier.value = [false, false, false];
      await tester.pump();

      expect(find.text('0 false'), findsOneWidget);
      expect(callCounts[0], 1);
      expect(find.text('1 false'), findsOneWidget);
      expect(callCounts[1], 3);
      expect(find.text('2 false'), findsOneWidget);
      expect(callCounts[2], 1);

      notifier.value = [true, false, false];
      await tester.pump();

      expect(find.text('0 true'), findsOneWidget);
      expect(callCounts[0], 2);
      expect(find.text('1 false'), findsOneWidget);
      expect(callCounts[1], 3);
      expect(find.text('2 false'), findsOneWidget);
      expect(callCounts[2], 1);

      notifier.value = [true, false, false];
      await tester.pump();

      expect(find.text('0 true'), findsOneWidget);
      expect(callCounts[0], 2);
      expect(find.text('1 false'), findsOneWidget);
      expect(callCounts[1], 3);
      expect(find.text('2 false'), findsOneWidget);
      expect(callCounts[2], 1);
    });

    testWidgets('create can use read without being lazy', (tester) async {
      await tester.pumpWidget(
        MultiProvider(
          providers: [
            Provider(create: (context) => 42),
            Provider(
              lazy: false,
              create: (context) => context.read<int>().toString(),
            ),
          ],
          child: Consumer<String>(
            builder: (c, value, _) {
              return Text(value, textDirection: TextDirection.ltr);
            },
          ),
        ),
      );

      expect(find.text('42'), findsOneWidget);
    });
    testWidgets('watch can be used inside InheritedProvider.update',
        (tester) async {
      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: InheritedProvider<String>(
            update: (c, _) {
              return c.watch<int>().toString();
            },
            child: Consumer<String>(
              builder: (c, value, _) {
                return Text(value, textDirection: TextDirection.ltr);
              },
            ),
          ),
        ),
      );
    });
    testWidgets(
        "select doesn't fail if it loads a provider that depends on other providers",
        (tester) async {
      await tester.pumpWidget(
        MultiProvider(
          providers: [
            Provider(create: (_) => 42),
            ProxyProvider<int, String>(
              create: (c) => '${c.read<int>()}',
              update: (c, _, __) => '${c.watch<int>() * 2}',
            ),
          ],
          child: Builder(
            builder: (context) {
              final value = context.select((String value) => value);
              return Text(value, textDirection: TextDirection.ltr);
            },
          ),
        ),
      );

      expect(find.text('84'), findsOneWidget);
    });

    testWidgets("don't call old selectors if the child rebuilds individually",
        (tester) async {
      final notifier = ValueNotifier(0);

      var buildCount = 0;
      final selector =
          MockSelector.identity<ValueNotifier<int>>(ValueNotifier(0));
      final child = Builder(builder: (c) {
        buildCount++;
        c.select<ValueNotifier<int>, ValueNotifier<int>>(selector);
        return Container();
      });

      await tester.pumpWidget(
        ChangeNotifierProvider.value(
          value: notifier,
          child: child,
        ),
      );

      expect(buildCount, 1);
      verify(selector(notifier)).called(1);
      verifyNoMoreInteractions(selector);

      tester.element(find.byWidget(child)).markNeedsBuild();
      await tester.pump();

      expect(buildCount, 2);
      verify(selector(notifier)).called(1);
      verifyNoMoreInteractions(selector);

      notifier.notifyListeners();
      await tester.pump();

      expect(buildCount, 2);
      verify(selector(notifier)).called(1);
      verifyNoMoreInteractions(selector);
    });

    testWidgets('selects throws inside click handlers', (tester) async {
      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: Builder(builder: (context) {
            return GestureDetector(
              behavior: HitTestBehavior.opaque,
              onTap: () {
                context.select((int a) => a);
              },
              child: Container(),
            );
          }),
        ),
      );

      expect(tester.takeException(), isNull);
      await tester.tap(find.byType(GestureDetector));

      expect(tester.takeException(), isAssertionError);
    });

    testWidgets('select throws if try to read dynamic', (tester) async {
      await tester.pumpWidget(
        Builder(builder: (c) {
          c.select<dynamic, dynamic>((dynamic i) => i);
          return Container();
        }),
      );

      expect(tester.takeException(), isAssertionError);
    });

    testWidgets('select throws ProviderNotFoundException', (tester) async {
      await tester.pumpWidget(
        Builder(builder: (c) {
          c.select((int i) => i);
          return Container();
        }),
      );

      expect(tester.takeException(), isA<ProviderNotFoundException>());
    });

    testWidgets('select throws if watch called inside the callback from build',
        (tester) async {
      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: Builder(builder: (context) {
            context.select((int i) {
              context.watch<int>();
              return i;
            });
            return Container();
          }),
        ),
      );

      expect(tester.takeException(), isAssertionError);
    });

    testWidgets('select throws if read called inside the callback from build',
        (tester) async {
      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: Builder(builder: (context) {
            context.select((int i) {
              context.read<int>();
              return i;
            });
            return Container();
          }),
        ),
      );

      expect(tester.takeException(), isAssertionError);
    });

    testWidgets('select throws if select called inside the callback from build',
        (tester) async {
      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: Builder(builder: (context) {
            context.select((int i) {
              context.select((int i) => i);
              return i;
            });
            return Container();
          }),
        ),
      );

      expect(tester.takeException(), isAssertionError);
    });

    testWidgets(
        'select throws if read called inside the callback on dependency change',
        (tester) async {
      var shouldCall = false;
      final child = Builder(builder: (context) {
        context.select((int i) {
          if (shouldCall) {
            context.read<int>();
          }
          // trigger selector call without rebuilding
          return 0;
        });
        return const Text('foo', textDirection: TextDirection.ltr);
      });

      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: child,
        ),
      );

      expect(find.text('foo'), findsOneWidget);
      shouldCall = true;
      await tester.pumpWidget(
        Provider.value(
          value: 21,
          child: child,
        ),
      );

      expect(tester.takeException(), isAssertionError);
    });

    testWidgets(
        'select throws if watch called inside the callback on dependency change',
        (tester) async {
      var shouldCall = false;
      final child = Builder(builder: (context) {
        context.select((int i) {
          if (shouldCall) {
            context.watch<int>();
          }
          // trigger selector call without rebuilding
          return 0;
        });
        return const Text('foo', textDirection: TextDirection.ltr);
      });

      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: child,
        ),
      );

      expect(find.text('foo'), findsOneWidget);
      shouldCall = true;
      await tester.pumpWidget(
        Provider.value(
          value: 21,
          child: child,
        ),
      );

      expect(tester.takeException(), isAssertionError);
    });

    testWidgets(
        'select throws if select called inside the callback on dependency change',
        (tester) async {
      var shouldCall = false;
      final child = Builder(builder: (context) {
        context.select((int i) {
          if (shouldCall) {
            context.select((int i) => i);
          }
          // trigger selector call without rebuilding
          return 0;
        });
        return const Text('foo', textDirection: TextDirection.ltr);
      });

      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: child,
        ),
      );

      expect(find.text('foo'), findsOneWidget);
      shouldCall = true;
      await tester.pumpWidget(
        Provider.value(
          value: 21,
          child: child,
        ),
      );

      expect(tester.takeException(), isAssertionError);
    });

    testWidgets('can call read inside didChangeDependencies', (tester) async {
      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: StatefulTest(
            didChangeDependencies: (context) {
              context.read<int>();
            },
            child: const Text('42', textDirection: TextDirection.ltr),
          ),
        ),
      );

      expect(find.text('42'), findsOneWidget);
    });

    testWidgets('select cannot be called inside didChangeDependencies',
        (tester) async {
      Object? error;
      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: StatefulTest(
            didChangeDependencies: (c) {
              try {
                c.select((int i) => i);
              } catch (err) {
                error = err;
              }
            },
            builder: (context) => Container(),
          ),
        ),
      );

      expect(error, isAssertionError);
    });

    testWidgets('select in initState throws', (tester) async {
      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: StatefulTest(
            initState: (c) {
              c.select((int i) => i);
            },
            child: Container(),
          ),
        ),
      );

      expect(tester.takeException(), isAssertionError);
    });

    testWidgets('watch in initState throws', (tester) async {
      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: StatefulTest(
            initState: (c) {
              c.watch<int>();
            },
            child: Container(),
          ),
        ),
      );

      expect(tester.takeException(), isAssertionError);
    });

    testWidgets('read in initState works', (tester) async {
      int? value;
      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: StatefulTest(
            initState: (c) {
              value = c.read<int>();
            },
            child: Container(),
          ),
        ),
      );

      expect(value, 42);
    });

    testWidgets('consumer can be removed and selector stops to be called',
        (tester) async {
      final selector = MockSelector.identity<int>(0);

      final child = Builder(builder: (c) {
        c.select<int, int>(selector);
        return Container();
      });

      await tester.pumpWidget(
        Provider.value(
          value: 0,
          child: child,
        ),
      );

      verify(selector(0)).called(1);
      verifyNoMoreInteractions(selector);

      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: Container(),
        ),
      );

      // necessary call because didChangeDependencies may be called even
      // if the widget will be unmounted in the same frame
      verify(selector(42)).called(1);
      verifyNoMoreInteractions(selector);

      await tester.pumpWidget(
        Provider.value(
          value: 84,
          child: Container(),
        ),
      );

      verifyNoMoreInteractions(selector);
    });

    testWidgets('context.select deeply compares maps', (tester) async {
      final notifier = ValueNotifier(<int, int>{});

      var buildCount = 0;
      final selector = MockSelector.identity<Map<int, int>>({});
      final child = Builder(builder: (c) {
        buildCount++;
        c.select<Map<int, int>, Map<int, int>>(selector);
        return Container();
      });

      await tester.pumpWidget(
        ValueListenableBuilder<Map<int, int>>(
          valueListenable: notifier,
          builder: (context, value, _) {
            return Provider.value(
              value: value,
              child: child,
            );
          },
        ),
      );

      expect(buildCount, 1);
      verify(selector(notifier.value)).called(1);
      verifyNoMoreInteractions(selector);

      notifier.value = {0: 0, 1: 1};
      await tester.pump();

      expect(buildCount, 2);
      verify(selector(notifier.value)).called(2);
      verifyNoMoreInteractions(selector);

      notifier.value = {0: 0, 1: 1};

      await tester.pump();

      expect(buildCount, 2);
      verify(selector(notifier.value)).called(1);
      verifyNoMoreInteractions(selector);
    });

    testWidgets('context.select deeply compares lists', (tester) async {
      final notifier = ValueNotifier(<int>[]);

      var buildCount = 0;
      final selector = MockSelector.identity<List<int>>([]);
      final child = Builder(builder: (c) {
        buildCount++;
        c.select<List<int>, List<int>>(selector);
        return Container();
      });

      await tester.pumpWidget(
        ValueListenableBuilder<List<int>>(
          valueListenable: notifier,
          builder: (context, value, _) {
            return Provider.value(
              value: value,
              child: child,
            );
          },
        ),
      );

      expect(buildCount, 1);
      verify(selector(notifier.value)).called(1);
      verifyNoMoreInteractions(selector);

      notifier.value = [0, 1];
      await tester.pump();

      expect(buildCount, 2);
      verify(selector(notifier.value)).called(2);
      verifyNoMoreInteractions(selector);

      notifier.value = [0, 1];
      await tester.pump();

      expect(buildCount, 2);
      verify(selector(notifier.value)).called(1);
      verifyNoMoreInteractions(selector);
    });

    testWidgets('context.select deeply compares iterables', (tester) async {
      final notifier = ValueNotifier<Iterable<int>>(<int>[]);

      var buildCount = 0;
      final selector = MockSelector.identity<Iterable<int>>({});
      final child = Builder(builder: (c) {
        buildCount++;
        c.select<Iterable<int>, Iterable<int>>(selector);
        return Container();
      });

      await tester.pumpWidget(
        ValueListenableBuilder<Iterable<int>>(
          valueListenable: notifier,
          builder: (context, value, _) {
            return Provider.value(
              value: value,
              child: child,
            );
          },
        ),
      );

      expect(buildCount, 1);
      verify(selector(notifier.value)).called(1);
      verifyNoMoreInteractions(selector);

      notifier.value = [0, 1];
      await tester.pump();

      expect(buildCount, 2);
      verify(selector(notifier.value)).called(2);
      verifyNoMoreInteractions(selector);

      notifier.value = [0, 1];
      await tester.pump();

      expect(buildCount, 2);
      verify(selector(notifier.value)).called(1);
      verifyNoMoreInteractions(selector);
    });

    testWidgets('context.select deeply compares sets', (tester) async {
      final notifier = ValueNotifier<Set<int>>(<int>{});

      var buildCount = 0;
      final selector = MockSelector.identity<Set<int>>({});
      final child = Builder(builder: (c) {
        buildCount++;
        c.select<Set<int>, Set<int>>(selector);
        return Container();
      });

      await tester.pumpWidget(
        ValueListenableBuilder<Set<int>>(
          valueListenable: notifier,
          builder: (context, value, _) {
            return Provider.value(
              value: value,
              child: child,
            );
          },
        ),
      );

      expect(buildCount, 1);
      verify(selector(notifier.value)).called(1);
      verifyNoMoreInteractions(selector);

      notifier.value = {0, 1};
      await tester.pump();

      expect(buildCount, 2);
      verify(selector(notifier.value)).called(2);
      verifyNoMoreInteractions(selector);

      notifier.value = {0, 1};
      await tester.pump();

      expect(buildCount, 2);
      verify(selector(notifier.value)).called(1);
      verifyNoMoreInteractions(selector);
    });

    testWidgets('context.watch listens to value changes', (tester) async {
      final child = Builder(builder: (context) {
        final value = context.watch<int>();
        return Text('$value', textDirection: TextDirection.ltr);
      });

      await tester.pumpWidget(
        Provider.value(
          value: 42,
          child: child,
        ),
      );

      expect(find.text('42'), findsOneWidget);

      await tester.pumpWidget(
        Provider.value(
          value: 24,
          child: child,
        ),
      );

      expect(find.text('24'), findsOneWidget);
    });
  });

  testWidgets('clears select dependencies for all dependents', (tester) async {
    var buildCountChild1 = 0;
    var buildCountChild2 = 0;

    final select1 = MockSelector<int, int>(0, (v) => 0);
    final select2 = MockSelector<int, int>(0, (v) => 0);

    Widget build(int value) {
      return Provider.value(
        value: value,
        child: Stack(
          textDirection: TextDirection.ltr,
          children: <Widget>[
            Builder(builder: (c) {
              buildCountChild1++;
              c.select<int, int>(select1.call);
              return Container();
            }),
            Builder(builder: (c) {
              buildCountChild2++;
              c.select<int, int>(select2.call);
              return Container();
            }),
          ],
        ),
      );
    }

    await tester.pumpWidget(build(0));

    expect(buildCountChild1, 1);
    expect(buildCountChild2, 1);
    verify(select1(0)).called(1);
    verifyNoMoreInteractions(select1);
    verify(select2(0)).called(1);
    verifyNoMoreInteractions(select2);

    await tester.pumpWidget(build(1));

    expect(buildCountChild1, 2);
    expect(buildCountChild2, 2);
    verify(select1(1)).called(2);
    verifyNoMoreInteractions(select1);
    verify(select2(1)).called(2);
    verifyNoMoreInteractions(select2);

    await tester.pumpWidget(build(2));

    expect(buildCountChild1, 3);
    expect(buildCountChild2, 3);
    verify(select1(2)).called(2);
    verifyNoMoreInteractions(select1);
    verify(select2(2)).called(2);
    verifyNoMoreInteractions(select2);
  });
}

class StatefulTest extends StatefulWidget {
  const StatefulTest({
    Key? key,
    this.initState,
    this.child,
    this.didChangeDependencies,
    this.builder,
    this.dispose,
  }) : super(key: key);

  final void Function(BuildContext c)? initState;
  final void Function(BuildContext c)? didChangeDependencies;
  final WidgetBuilder? builder;
  final Widget? child;
  final void Function(BuildContext c)? dispose;

  @override
  _StatefulTestState createState() => _StatefulTestState();
}

class _StatefulTestState extends State<StatefulTest> {
  @override
  void initState() {
    super.initState();
    widget.initState?.call(context);
  }

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    widget.didChangeDependencies?.call(context);
  }

  @override
  void dispose() {
    widget.dispose?.call(context);
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    if (widget.builder != null) {
      return widget.builder!(context);
    }
    return widget.child!;
  }
}

class MockSelector<T, R> extends Mock {
  MockSelector(this.fallback, R Function(T v) cb) {
    when(this(any)).thenAnswer((i) {
      return cb(i.positionalArguments.first as T);
    });
  }

  static MockSelector<T, T> identity<T>(T fallback) {
    return MockSelector<T, T>(fallback, (v) => v);
  }

  final R fallback;

  R call(T? v) => super.noSuchMethod(
        Invocation.method(#call, [v]),
        returnValue: fallback,
        returnValueForMissingStub: fallback,
      ) as R;
}