Flutter 在Dart中进行单元测试时，Mockito存根挂起等待调用

我在Dart中使用Mockito来测试异步代码

我有一个异步调用的类：

class StorageService {
  FirebaseStorage _storage;
  
  Future<bool> uploadMyImage(MyImage myImage) async {
    final path = "/${myImage.id}.jpg";

    try {
      await _storage.ref(path).putData(myImage.data);
      return true;
    } on Exception {
      return false;
    }
  }
}

单元测试从未完成，因为它正在等待

等待mockUploadTask

。我怎样才能使它完整

@GenerateMocks([FirebaseStorage, Reference, UploadTask, TaskSnapshot])
void main() {
  test('uploadMyImage returns true on successful upload', () async {
    // 1. given
    final mockFirebaseStorage = MockFirebaseStorage();
    final subject = StorageService(firebaseStorage: mockFirebaseStorage);

    final myImage = Generators.myImage();
    final mockReference = MockReference();
    final mockUploadTask = MockUploadTask();
    final mockTaskSnapshot = MockTaskSnapshot();

    // 2. when
    final path = "/${myImage.id}.jpg";

    when(mockFirebaseStorage.ref(path)).thenReturn(mockReference);
    when(mockReference.putData(myImage.data)).thenAnswer((_) => mockUploadTask);
    when(await mockUploadTask).thenAnswer((_) => mockTaskSnapshot);

    final result = await subject.uploadMyImage(myImage);

    // 3. then
    expect(result, true);
  });
}