单元测试 Realm 用 Mockito 包装了 LiveData

Question

我正在尝试 Realm 以及包括 LiveData 在内的 Android 架构组件。

我一直在关注谷歌的应用程序架构指南：

https://developer.android.com/topic/libraries/architecture/guide.html

。用领域代替房间。

从实现的角度来看，我一切都在工作，但是在尝试编写单元测试时遇到了Mockito的问题，我还无法解决。

我在下面展示了我的测试，其中包含一些注释掉的行以及到目前为止我所尝试的内容和结果的解释：

@Test
public void loadCustomModelObjectsFromNetwork() throws IOException {
// Prepare DAO
MutableLiveData<List<CustomModelObject>> dbData = new MutableLiveData<>();
// Compilation error
//when(dao.getCustomModelObjects()).thenReturn(dbData);
// Runtime exc.
//doReturn(dbData).when(dao).getCustomModelObjects();
// Runtime exc.
//java.lang.ClassCastException: 
//android.arch.lifecycle.MutableLiveData cannot be cast to LiveRealmResults
doAnswer(new Answer() {
@Override
public Object answer(InvocationOnMock i) throws Throwable {
// Made various attempts to convert to LiveRealmResults here 
return dbData;
}
}).when(dao).getCustomModelObjects();
/*
org.mockito.exceptions.misusing.WrongTypeOfReturnValue:
MutableLiveData cannot be returned by getCustomModelObjectss()
getCustomModelObjects() should return LiveRealmResults
*/
// Prepare REST service response
List<CustomModelObject> customModelObjects = new ArrayList<>();
CustomModelObject repo = new CustomModelObject();
repo.setDescription("Desc1");
customModelObjects.add(repo);
CustomModelObjectsResponse response = new CustomModelObjectsResponse();
response.setCustomModelObjects(customModelObjects);
DocumentWrapper<CustomModelObjectsResponse> items = new DocumentWrapper<>();
items.setBody(response);
LiveData<ApiResponse<DocumentWrapper<CustomModelObjectsResponse>>> call = successCall(items);
when(retrofitService.getCustomModelObjects()).thenReturn(call);
when(service.getService()).thenReturn(retrofitService);
// Item under test
LiveData<Resource<List<CustomModelObject>>> data = repository.getCustomModelObjects();
// Assertions
verify(dao).getCustomModelObjects();
verifyNoMoreInteractions(service);
Observer observer = mock(Observer.class);
data.observeForever(observer);
verifyNoMoreInteractions(service);
verify(observer).onChanged(Resource.loading(null));
MutableLiveData<List<CustomModelObject>> updatedDbData = new MutableLiveData<>();
//when(dao.getCustomModelObjects()).thenReturn(updatedDbData);
doReturn(updatedDbData).when(dao).getCustomModelObjects();
dbData.postValue(null);
verify(retrofitService).getCustomModelObjects();
verify(dao).save(customModelObjects);
updatedDbData.postValue(customModelObjects);
verify(observer).onChanged(Resource.success(repo));
}

尽管在我的实现中它工作正常并且可以从单元测试中的LiveRealmResults<CustomModelObject>派生LiveData<List<CustomModelObject>>但我似乎无法将其与 Mockito 一起使用。

有关我的设置的更多实现详细信息，请参阅此处：

使用 Realm 和 LiveData。将 LiveData> 转换为 LiveData>

谢谢 保罗。

更新

when(dao.getCustomModelObjects()).thenReturn(dbData);
has the following compilation error:
error: no suitable method found for 
thenReturn(MutableLiveData<List<CustomModelObject>>)
method OngoingStubbing.thenReturn(LiveRealmResults<CustomModelObject>) is not applicable
(argument mismatch; MutableLiveData<List<CustomModelObject>> cannot be converted to LiveRealmResults<CustomModelObject>)
method OngoingStubbing.thenReturn(LiveRealmResults<CustomModelObject>,LiveRealmResults<CustomModelObject>...) is not applicable
(argument mismatch; MutableLiveData<List<CustomModelObject>> cannot be converted to LiveRealmResults<CustomModelObject>)

Answer 1

public RealmLiveData<CustomModelObject> getCustomModelObjects() {
return asLiveData(realm.where(CustomModelObject.class).findAllAsync());
}

应该是

public LiveData<List<<CustomModelObject>> getCustomModelObjects() {
return asLiveData(realm.where(CustomModelObject.class).findAllAsync());
}

然后，您的when(...)应该不再有编译错误。