Flutter TDD项目测试报Bad state错误，求正确运行测试方案

错误信息 #

Bad state: No method stub was called from within when(). Was a real method called, or perhaps an extension method?

问题代码 #

Repository代码 #

abstract class HomeRepository {
    Future<Either<Failure,BaseModel>> testCase({required ApiRequest apiRequest});
}

UseCase代码 #

class TestCase {
  HomeRepository homeRepository;
  TestCase({required this.homeRepository});
  Future<Either<Failure,BaseModel>>call({required ApiRequest apiRequest})async{
    return await homeRepository.testCase(apiRequest: apiRequest);
  }
}

测试代码（原错误版本） #

class HomeTest extends Mock implements HomeRepository{
  @override
  Future<Either<Failure,BaseModel>> testCase({required ApiRequest apiRequest})async{
     return await Right(AppModel.otpVerify);
  }
}

void main(){
  ApiRequest apiRequest = ApiRequest(method: ApiMethod.post, endPoint: '/');
  late HomeTest homeTest;
  late TestCase testCase;
    setUp(() {
      homeTest = HomeTest();
      testCase = TestCase(homeRepository: homeTest);
    });

  test('testcase', () async {
    // Setup
    when(homeTest.testCase(apiRequest: apiRequest)).thenAnswer((_) async => right(AppModel.otpVerify));
    // Action
    final result = await testCase(apiRequest: apiRequest);
    // Verification
    expect(result, right(AppModel.otpVerify));
  });
}

错误原因 #

你在自定义的HomeTest Mock类中手动重写了testCase方法，导致调用when(homeTest.testCase(...))时，实际执行的是你重写的真实方法，而非Mock库提供的用于生成stub的代理方法。Mock库需要接管方法调用逻辑才能记录stub，手动重写会破坏这一机制。

解决方案 #

去掉HomeTest类中对testCase方法的重写，让Mock类自动处理方法的stub逻辑：

// 仅保留Mock继承和接口实现，移除手动重写的方法
class HomeTest extends Mock implements HomeRepository{}

void main(){
  ApiRequest apiRequest = ApiRequest(method: ApiMethod.post, endPoint: '/');
  late HomeTest homeTest;
  late TestCase testCase;
    setUp(() {
      homeTest = HomeTest();
      testCase = TestCase(homeRepository: homeTest);
    });

  test('testcase', () async {
    // Setup
    when(homeTest.testCase(apiRequest: apiRequest)).thenAnswer((_) async => right(AppModel.otpVerify));
    // Action
    final result = await testCase(apiRequest: apiRequest);
    // Verification
    expect(result, right(AppModel.otpVerify));
  });
}

补充说明 #

如果ApiRequest未正确实现==和hashCode方法，可能会导致stub匹配失败。可以通过两种方式解决：

1. 为ApiRequest类重写==和hashCode方法
2. 在when中使用匹配器替代具体实例：

   when(homeTest.testCase(apiRequest: any(named: 'apiRequest')))
       .thenAnswer((_) async => right(AppModel.otpVerify));
   

内容的提问来源于stack exchange，提问作者Anas Sa