如何在 Flutter 中测试（单元测试）BehaviorSubject？

Question

我想测试管理我的表单的控制器流。在这里，我尝试测试连接到验证器的电子邮件控制器。

我设法通过接收器方法添加控制器值并通过流方法恢复。

宣言

  final emailController = BehaviorSubject<String>();

  Stream<String> get email => emailController.stream.transform(validateEmail);

  Function(String) get changeEmail => emailController.sink.add;

验证器进行测试

final validateEmail =
      StreamTransformer<String, String>.fromHandlers(handleData: (email, sink) {
    final emailRegExp = new RegExp(
      r"^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,253}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,253}[a-zA-Z0-9])?)*$",
      caseSensitive: false,
      multiLine: false,
    );

    emailRegExp.hasMatch(email).toString();
    if (email.contains('@')) {
      sink.add(email);
    } else {
      sink.addError('Enter a valid email');
    }
  });

单元测试

void main() {
  UserProfilEditBloc userProfilEditBloc = new UserProfilEditBloc();

  test('Email check BehaviorSubject', () {
    userProfilEditBloc.changeEmail('testtest'); //Expected @

    expect(userProfilEditBloc.email, emits('Enter a valid email'));
  });
}

错误信息

00:02 +0 -1: Email check BehaviorSubject [E]
  Enter a valid email
  dart:async                                              _StreamController.addError
  package:async/src/result/error.dart 30:10               ErrorResult.addTo
  package:async/src/stream_queue.dart 959:29              _TransactionRequest.update
  package:async/src/stream_queue.dart 426:31              StreamQueue._updateRequests
  package:async/src/stream_queue.dart 514:5               StreamQueue._addResult
  package:async/src/stream_queue.dart 486:9               StreamQueue._ensureListening.<fn>
  dart:async                                              _EventSinkWrapper.addError
  package:nexo/src/blocs/UserProfilEditBloc.dart 29:12    new _UserProfilEditBloc&Object&InputValidators.<fn>
  ===== asynchronous gap ===========================
  dart:async                                              _BoundSinkStream.listen
  package:rxdart/src/observables/observable.dart 1724:20  Observable.listen
  package:async/src/stream_queue.dart 483:31              StreamQueue._ensureListening
  package:async/src/stream_queue.dart 542:7               StreamQueue._addRequest
  package:async/src/stream_queue.dart 299:5               StreamQueue.startTransaction
  package:test_api                                        expect
  package:flutter_test/src/widget_tester.dart 196:3       expect
  test/register_form_test.dart 15:5                       main.<fn>

00:02 +0 -1: Some tests failed.

如果我忘记@，验证器填充sink.addError()就会导致这个错误。当验证器执行 sink.add() 时，一切都会顺利进行。

Answer 1

我相信，你所缺少的是：emitsError。 BehaviourSubject有一个缓存值，因此您将如何测试它：

  test('Email check BehaviorSubject', () {
    expectLater(userProfileEditBloc.email, emitsInOrder([
      emits(anything), // current email if you want to check for that
      emitsError('Enter a valid email'),\
      // emitsDone // in case you also close the stream with the error
    ]));

    userProfilEditBloc.changeEmail('testtest'); //Expected @
  });

rxDart 测试文件通常为如何测试功能提供了一个很好的起点。