带有包装数组的测试流

Question

我正在尝试测试函数 emitArray 发出一个 Response.Success 其值为 ['test'].
如果我发出 List<String> 一切都按预期工作，但是一旦我将结果列表包装在 Response<List<String>> 中，测试就会失败。

结果发出，但与预期结果比较失败。
我想知道它是否与 Response.Success 中 == 的实现有关，我使用的是 IDE 提供的默认实现。

这不是我的真实代码，它只是一个更容易理解的简单示例，用于尝试找出问题。

这是我要测试的class：

class ListResponse {
  final _array = BehaviorSubject<Response<List<String>>>();

  Stream<Response<List<String>>> get array => _array.stream;

  Future<void> emitArray() async {
    _array.add(Response.success(['test']));
  }

  void dispose() {
    _array.close();
  }
}

这是我的测试：

void main() {
  ListResponse underTest;
  setUp(() {
    underTest = ListResponse();
  });

  test('It should emit array', () {
    final array = Response.success(['test']);

    expect(
      underTest.array,
      emitsInOrder([
        array,
        emitsDone,
      ]),
    );

    underTest.emitArray();

    underTest.dispose();
  });
}

这是它抛出的错误：

Expected: should do the following in order:
          • emit an event that SuccessResponse<List<String>>:<SuccessResponse{value: [test]}>
          • be done
  Actual: <Instance of 'BehaviorSubject<Response<List<String>>>'>
   Which: emitted • SuccessResponse{value: [test]}
                  x Stream closed.
            which didn't emit an event that SuccessResponse<List<String>>:<SuccessResponse{value: [test]}>

这是回应class

class Response<T> {
  Response._();

  factory Response.success(T value) = SuccessResponse<T>;
  factory Response.error(Exception error) = ErrorResponse<T>;
}

class ErrorResponse<T> extends Response<T> {
  ErrorResponse(this.error): super._();

  final Exception error;

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
          other is ErrorResponse &&
              runtimeType == other.runtimeType &&
              error == other.error;

  @override
  int get hashCode => error.hashCode;

  @override
  String toString() {
    return 'ErrorResponse{error: $error}';
  }
}

class SuccessResponse<T> extends Response<T> {
  SuccessResponse(this.value): super._();

  final T value;

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
          other is SuccessResponse &&
              runtimeType == other.runtimeType &&
              value == other.value;

  @override
  int get hashCode => value.hashCode;

  @override
  String toString() {
    return 'SuccessResponse{value: $value}';
  }
}

Answer 1

I'm wondering if it's related to the implementation of == in Response.Success

没错。此特定测试失败，因为您无法将列表与 ==:

进行比较

abstract class List<E> implements EfficientLengthIterable<E> {
  ...
  /**
  * Whether this list is equal to [other].
  *
  * Lists are, by default, only equal to themselves.
  * Even if [other] is also a list, the equality comparison
  * does not compare the elements of the two lists.
  */
 bool operator ==(Object other);
}

作为解决方法，您可以更改实现以比较对象的字符串表示形式：

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
      other is SuccessResponse &&
          runtimeType == other.runtimeType &&
          value.toString() == other.value.toString();

有趣的是，传递未包装的 List<String>s 对象通过了测试。发生这种情况是因为 StreamMatcher 使用 matcher 包中的 equals() 来匹配事件，并且 equals() can match lists and maps。它首先尝试匹配 == 的对象，然后检查它们是否是 Iterable/Set/Map （并递归地深度匹配它们），然后报告不匹配错误。

带有包装数组的测试流

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