Flutter bloc 测试——emitsInorder 不发出初始状态

我真的很困惑如何让集团发出初始状态。 bloc.state 发出最新状态。由于在新的 bloc 库中没有可用的 @override initialState，initialState 被传递给 super 构造函数。但是 bloc 仍然不发出 initialState，在这种情况下是 Empty()。
number_trivia_bloc.dart

import 'package:clean_architecture/core/error/failure.dart';
import 'package:clean_architecture/core/utils/input_converter.dart';
import 'package:clean_architecture/features/number_trivia/domain/usecases/get_concrete_number_trivia_repository.dart';
import 'package:clean_architecture/features/number_trivia/domain/usecases/get_random_number_trivia.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'number_trivia_state.dart';
import 'number_trivia_event.dart';

const SERVER_FAILURE = 'Server failure';
const CACHE_FAILURE = 'Cache failure';
const INVALID_INPUT_FAILURE =
    'Invalid Input Failure - The input should not be a negative integer or zero';

class NumberTriviaBloc extends Bloc<NumberTriviaEvent, NumberTriviaState> {
  final GetConcreteNumberTrivia getConcreteNumberTrivia;
  final GetRandomNumberTrivia getRandomNumberTrivia;
  final InputConverter inputConverter;

  NumberTriviaBloc({
    // Changed the name of the constructor parameter (cannot use 'this.')
    @required GetConcreteNumberTrivia concrete,
    @required GetRandomNumberTrivia random,
    @required this.inputConverter,
    // Asserts are how you can make sure that a passed in argument is not null.
    // We omit this elsewhere for the sake of brevity.
  })  : assert(concrete != null),
        assert(random != null),
        assert(inputConverter != null),
        getConcreteNumberTrivia = concrete,
        getRandomNumberTrivia = random,
        super(Empty());

  @override
  Stream<NumberTriviaState> mapEventToState(
    NumberTriviaEvent event,
  ) async* {
    if (event is GetTriviaForConcreteNumber) {
      final inputEither =
          inputConverter.stringToUnsignedInteger(event.numberString);
      yield* inputEither.fold(
        (failure) async* {
          yield Error(message: INVALID_INPUT_FAILURE);
        },
        (integer) async* {
          yield Loading();
        },
      );
    }
  }
}

number_trivia_bloc_test.dart

import 'package:clean_architecture/core/utils/input_converter.dart';
import 'package:clean_architecture/features/number_trivia/data/models/number_trivia_model.dart';
import 'package:clean_architecture/features/number_trivia/domain/entities/number_trivia.dart';
import 'package:clean_architecture/features/number_trivia/domain/usecases/get_concrete_number_trivia_repository.dart';
import 'package:clean_architecture/features/number_trivia/domain/usecases/get_random_number_trivia.dart';
import 'package:clean_architecture/features/number_trivia/presentation/bloc/number_trivia_bloc.dart';
import 'package:dartz/dartz.dart';
import 'package:flutter_test/flutter_test.dart';
import 'package:clean_architecture/features/number_trivia/presentation/bloc/number_trivia_state.dart';
import 'package:clean_architecture/features/number_trivia/presentation/bloc/number_trivia_event.dart';

import 'package:mockito/mockito.dart';

class MockGetConcreteNumberTrivia extends Mock
    implements GetConcreteNumberTrivia {}

class MockGetRandomNumberTrivia extends Mock implements GetRandomNumberTrivia {}

class MockInputConverter extends Mock implements InputConverter {}

void main() {
  NumberTriviaBloc bloc;
  MockGetConcreteNumberTrivia mockGetConcreteNumberTrivia;
  MockGetRandomNumberTrivia mockGetRandomNumberTrivia;
  MockInputConverter mockInputConverter;

  setUp(() {
    mockGetConcreteNumberTrivia = MockGetConcreteNumberTrivia();
    mockGetRandomNumberTrivia = MockGetRandomNumberTrivia();
    mockInputConverter = MockInputConverter();

    bloc = NumberTriviaBloc(
      concrete: mockGetConcreteNumberTrivia,
      random: mockGetRandomNumberTrivia,
      inputConverter: mockInputConverter,
    );
  });
  test('initialState should be Empty', () {
    // assert
    expect(bloc.state, equals(Empty()));
  });

  group('GetTriviaForNumber', () {
    String str = '1';
    int parsedStr = int.parse(str);
    NumberTrivia tTrivia =
        NumberTriviaModel(text: 'test text', number: parsedStr);
    test('Should convert a string to an unsigned integer', () async {
      //arrange
      when(mockInputConverter.stringToUnsignedInteger(any))
          .thenReturn(Right(parsedStr));
      //act
      bloc.add(GetTriviaForConcreteNumber(str));
      await untilCalled(mockInputConverter.stringToUnsignedInteger(str));
      //assert
      verify(mockInputConverter.stringToUnsignedInteger(any));
    });

    test('Should return [Error] for InvalidInputFailure', () async {
      //arrange
      when(mockInputConverter.stringToUnsignedInteger(any))
          .thenReturn(Left(InvalidInputFailure()));
      //assert later
      final expected = [
        Empty(),
        Error(message: INVALID_INPUT_FAILURE),
      ];
      expectLater(bloc, emitsInOrder(expected));
      //act
      bloc.add(GetTriviaForConcreteNumber(str));
    });
  });
}

它应该可以工作，但我得到的只是这个错误在向我尖叫。我尝试 bloc.cast(), bloc.asBroadcastStream()。似乎没有任何效果。所以，请有人帮我解决这个问题。提前致谢。

最佳答案

与 flutter_bloc 6.0.0 相比有一些变化
您可以通过以下方式检查初始状态

test('initial state is correct', () {
  expect(bloc.state, Empty());
});

这里提到:
Regression: initial state is not emited anymore

关于Flutter bloc 测试——emitsInorder 不发出初始状态，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/64566439/