actionBlocTest<B extends ActionBlocBase<State, Action>, State, Action> function

@isTest void actionBlocTest<B extends ActionBlocBase<State, Action>, State, Action>(String description, { FutureOr<void> setUp()?, required B build(), State seed()?, void act(B bloc)?, Duration? wait, int skip = 0, dynamic expect()?, dynamic expectActions()?, void verify(B bloc)?, dynamic errors()?, FutureOr<void> tearDown()?, dynamic tags, })

Creates a new bloc-specific test case with the given description. blocTest will handle asserting that the bloc emits the expected states (in order) after act is executed. blocTest also handles ensuring that no additional states are emitted by closing the bloc stream before evaluating the expectation.

setUp is optional and should be used to set up any dependencies prior to initializing the bloc under test. setUp should be used to set up state necessary for a particular test case. For common set up code, prefer to use setUp from package:test/test.dart.

build should construct and return the bloc under test.

seed is an optional Function that returns a state which will be used to seed the bloc before act is called.

act is an optional callback which will be invoked with the bloc under test and should be used to interact with the bloc.

skip is an optional int which can be used to skip any number of states. skip defaults to 0.

wait is an optional Duration which can be used to wait for async operations within the bloc under test such as debounceTime.

expect is an optional Function that returns a Matcher which the bloc under test is expected to emit after act is executed.

verify is an optional callback which is invoked after expect and can be used for additional verification/assertions. verify is called with the bloc returned by build.

errors is an optional Function that returns a Matcher which the bloc under test is expected to throw after act is executed.

tearDown is optional and can be used to execute any code after the test has run. tearDown should be used to clean up after a particular test case. For common tear down code, prefer to use tearDown from package:test/test.dart.

tags is optional and if it is passed, it declares user-defined tags that are applied to the test. These tags can be used to select or skip the test on the command line, or to do bulk test configuration.

blocTest(
  'CounterBloc emits [1] when increment is added',
  build: () => CounterBloc(),
  act: (bloc) => bloc.add(CounterEvent.increment),
  expect: () => [1],
);

blocTest can optionally be used with a seeded state.

blocTest(
  'CounterBloc emits [10] when seeded with 9',
  build: () => CounterBloc(),
  seed: () => 9,
  act: (bloc) => bloc.add(CounterEvent.increment),
  expect: () => [10],
);

blocTest can also be used to skip any number of emitted states before asserting against the expected states. skip defaults to 0.

blocTest(
  'CounterBloc emits [2] when increment is added twice',
  build: () => CounterBloc(),
  act: (bloc) {
    bloc
      ..add(CounterEvent.increment)
      ..add(CounterEvent.increment);
  },
  skip: 1,
  expect: () => [2],
);

blocTest can also be used to wait for async operations by optionally providing a Duration to wait.

blocTest(
  'CounterBloc emits [1] when increment is added',
  build: () => CounterBloc(),
  act: (bloc) => bloc.add(CounterEvent.increment),
  wait: const Duration(milliseconds: 300),
  expect: () => [1],
);

blocTest can also be used to verify internal bloc functionality.

blocTest(
  'CounterBloc emits [1] when increment is added',
  build: () => CounterBloc(),
  act: (bloc) => bloc.add(CounterEvent.increment),
  expect: () => [1],
  verify: (_) {
    verify(() => repository.someMethod(any())).called(1);
  }
);

Note: when using blocTest with state classes which don't override == and hashCode you can provide an Iterable of matchers instead of explicit state instances.

blocTest(
 'emits [StateB] when EventB is added',
 build: () => MyBloc(),
 act: (bloc) => bloc.add(EventB()),
 expect: () => [isA<StateB>()],
);

If tags is passed, it declares user-defined tags that are applied to the test. These tags can be used to select or skip the test on the command line, or to do bulk test configuration. All tags should be declared in the package configuration file. The parameter can be an Iterable of tag names, or a String representing a single tag.

Implementation

@isTest
void actionBlocTest<B extends ActionBlocBase<State, Action>, State, Action>(
  String description, {
  FutureOr<void> Function()? setUp,
  required B Function() build,
  State Function()? seed,
  void Function(B bloc)? act,
  Duration? wait,
  int skip = 0,
  dynamic Function()? expect,
  dynamic Function()? expectActions,
  void Function(B bloc)? verify,
  dynamic Function()? errors,
  FutureOr<void> Function()? tearDown,
  dynamic tags,
}) {
  final actions = <Action>[];
  late StreamSubscription<Action> subscription;

  blocTest(
    description,
    setUp: setUp,
    build: () {
      final bloc = build();
      subscription = bloc.actions.listen(actions.add);
      return bloc;
    },
    seed: seed,
    act: act,
    wait: wait,
    skip: skip,
    expect: expect,
    verify: (B bloc) {
      if (expectActions != null) {
        final dynamic expected = expectActions();
        // shallowEquality = '$actions' == '$expected';
        try {
          test.expect(actions, test.wrapMatcher(expected));
        } on test.TestFailure catch (e) {
          if (/* shallowEquality || */ expected is! List<State>) rethrow;
          final diff = _diff(expected: expected, actual: actions);
          final message = '${e.message}\n$diff';
          // ignore: only_throw_errors
          throw test.TestFailure(message);
        }
      }
      subscription.cancel();
      verify?.call(bloc);
    },
    errors: errors,
    tearDown: tearDown,
    tags: tags,
  );
}