java - 单元测试android : How to return function not to be null when calls another function return and use

Question

我有一个 FileRepository 类来填充 MutableLiveData。我在那里有两个功能。一种是调用 Web 服务并设置列表 (getAllFilms)。另一个是使用第一个函数 List (getFilmData) 分配 MutableLiveData。我尝试为 MutableLiveData 编写单元测试。你能帮助我吗？该函数数据始终为空。

public class FilmRepositoryTest

@Mock
FilmRepository frepo;

@Rule
public InstantTaskExecutorRule instantTaskExecutorRule = new InstantTaskExecutorRule();


@Before
public void setUp() throws Exception {
}

@Test
public void getFilmData_forData() throws IOException {
    ArrayList<film> filmlistesi = new ArrayList<>();
    MutableLiveData<List<film>> bilgi = new MutableLiveData<>();
    String arama = "ankara";
    filmlistesi.add(new film("Behzat Ç.: Bir Ankara Polisiyesi","2010–2019","tt1795096","series","https://m.media-amazon.com/images/M/MV5BZDZjY2I5ZjEtZGE2MS00ZjRmLTlmMGEtMDQ5ZmZhZWJjYzk3XkEyXkFqcGdeQXVyNDg4MjkzNDk@._V1_SX300.jpg"));

    when(frepo.getAllFilms(arama)).thenReturn(filmlistesi);
    bilgi.setValue(filmlistesi);
    System.out.println(frepo.getFilmData(arama)); // print(NULL)
    System.out.println(bilgi.getValue());         // print(filmlistesi)
    assertEquals(frepo.getFilmData(arama),bilgi.getValue());

}

<小时/>

public class FilmRepository

public MutableLiveData<List<film>> getFilmData(String a) throws IOException {
    MutableLiveData<List<film>> data = new MutableLiveData<>();
    data.setValue(getAllFilms(a));
    return data;
}

public ArrayList getAllFilms(String filmName) throws IOException {
    ArrayList<film> dataset = new ArrayList<>();
    return dataset;
}

Answer 1

LiveData 或 MutableLiveData 必须有一个 Observer 集，否则返回 null

Observer<List<film>> observer = new Observer<List<film>>() {

        @Override
        public void onChanged(@Nullable List<film> films) {
            assertEquals(frepo.getFilmData(arama), films.getValue());
            biligi.removeObserver(this)
        }

};

bilgi.observeForever(observer);
bilgi.setValue(filmlistesi);