如何测试http Request对象相等性？如何用equatable处理http包对象？

一、为什么http.Request相等性测试失败 #

http.Request类默认的==运算符是引用相等，即只有两个变量指向同一个对象实例时才会返回true。你创建的request和request2是两个独立的实例，哪怕内容完全一致，默认的equals匹配器也会判定它们不相等。

二、测试http.Request相等性的两种方案 #

方案1：自定义测试匹配器 #

直接编写一个自定义Matcher，对比Request的核心属性（method、url、body、headers等），实现内容相等的判断：

import 'package:http/http.dart' as http;
import 'package:test/test.dart';

// 自定义匹配器，对比Request的核心属性
Matcher requestEquals(http.Request expected) => _RequestEqualsMatcher(expected);

class _RequestEqualsMatcher extends Matcher {
  final http.Request _expected;

  _RequestEqualsMatcher(this._expected);

  @override
  bool matches(dynamic actual, Map matchState) {
    if (actual is! http.Request) return false;
    // 按需添加需要对比的属性，比如body、headers等
    return actual.method == _expected.method &&
        actual.url == _expected.url &&
        actual.body == _expected.body &&
        mapEquals(actual.headers, _expected.headers);
  }

  @override
  Description describe(Description description) {
    return description.add('Request: ${_expected.method} ${_expected.url}');
  }
}

// 测试用例
test('equality test', () async {
  final uri = baseUri.replace(path: 'account/login');
  final request = http.Request('POST', uri);
  final request2 = http.Request('POST', uri);
  
  // 使用自定义匹配器替代默认的equals
  expect(request, requestEquals(request2));
});

方案2：用Equatable包装Request类 #

通过包装第三方类，借助Equatable实现内容相等的判断：

import 'package:equatable/equatable.dart';
import 'package:http/http.dart' as http;

// 包装http.Request，用Equatable管理相等性判断
class EquatableRequest extends Equatable {
  final http.Request request;

  const EquatableRequest(this.request);

  // 列出需要参与相等性判断的核心属性
  @override
  List<Object?> get props => [
        request.method,
        request.url,
        request.body,
        request.headers,
      ];
}

// 测试用例
test('equality test', () async {
  final uri = baseUri.replace(path: 'account/login');
  final request = http.Request('POST', uri);
  final request2 = http.Request('POST', uri);
  
  expect(EquatableRequest(request), equals(EquatableRequest(request2)));
});

三、在http.Response上使用Equatable包 #

同样采用包装类的方式，将http.Response包裹后用Equatable管理相等性：

import 'package:equatable/equatable.dart';
import 'package:http/http.dart' as http;

class EquatableResponse extends Equatable {
  final http.Response response;

  const EquatableResponse(this.response);

  @override
  List<Object?> get props => [
        response.statusCode,
        response.body,
        response.headers,
        // 如果需要对比请求信息，可添加以下字段
        response.request?.method,
        response.request?.url,
      ];

  // 可选：添加getter简化属性访问
  int get statusCode => response.statusCode;
  String get body => response.body;
}

// 测试示例
test('response equality test', () {
  final response1 = http.Response('{"success": true}', 200);
  final response2 = http.Response('{"success": true}', 200);
  
  expect(EquatableResponse(response1), equals(EquatableResponse(response2)));
});

四、结合verify验证API调用正确性 #

如果用Mockito等mock库验证API调用，可以结合自定义匹配器来判断是否调用了正确的Request：

import 'package:http/http.dart' as http;
import 'package:mockito/mockito.dart';
import 'package:test/test.dart';

// Mock http.Client
class MockClient extends Mock implements http.Client {}

test('verify correct API endpoint is called', () async {
  final mockClient = MockClient();
  final targetUri = baseUri.replace(path: 'account/login');
  final expectedRequest = http.Request('POST', targetUri);

  // 设置mock返回
  when(mockClient.send(argThat(requestEquals(expectedRequest))))
      .thenAnswer((_) async => http.StreamedResponse(
            Stream.value([]),
            200,
          ));

  // 调用你要测试的业务方法（该方法内部使用mockClient发送请求）
  await yourApiLoginFunction(mockClient);

  // 验证是否按预期调用了send方法
  verify(mockClient.send(argThat(requestEquals(expectedRequest)))).called(1);
});

内容的提问来源于stack exchange，提问作者zex_rectooor