Mockito http。在类型转换中，客户端类型“Null”不是类型“Future”的子类型

Question

我正在使用Mockito在Flutter应用程序中对http请求应用单元测试。

要测试的代码：

@GenerateMocks([http.Client])
void main() {
  late GdprDataSourceImpl dataSource;
  late MockClient mockHttpClient;

  setUp(() {
    mockHttpClient = MockClient();
    dataSource = GdprDataSourceImpl(
      httpClient: mockHttpClient,
      baseUrl: '',
    );
  });

  group('post Gdpr', () {
    const status = true;
    final url = Uri.parse('/gdpr/consent');

    const body = {
      'status': status,
    };

    final errorMessage = fixture('error_response.json');
    
    test('should perform a POST request to /auth/otp', () async {
      when(mockHttpClient.post(url, body: body)).thenAnswer(
        (_) async => http.Response('', 201),
      );

      await dataSource.postGdpr(status: status);

      verify(mockHttpClient.post(url, body: body));
    });
  });
}

我得到了以下错误：“Null”类型不是类型转换中“Future”类型的子类型

已经使用构建运行器成功生成了模拟

我还尝试更新模拟类并将返回值更改为

returnValue: Future<http.Response?>

我得到:键入“未来”

Answer 1

因此，解决方案是使用package:http提供的MockClient类，而不是使用mockito。

  group('post Gdpr success', () {
    Future<http.Response> requestHandler(http.Request request) async {
      final apiResponse = fixture('gdpr_response.json');
      return http.Response(apiResponse, 201);
    }

    setUp(() {
      mockHttpClient = MockClient(requestHandler);

      dataSource = GdprDataSourceImpl(
        httpClient: mockHttpClient,
        baseUrl: '',
      );
    });

    test('should perform a POST request to /gdpr/consent', () async {
      final result = await dataSource.postGdpr(status: status);
      expect(result, gdprResponse);
    });
  });