android - 如何在 Android 的单元测试中模拟 Picasso？

Question

我有使用 Picasso 库的代码。

 @Inject
 public RegistrationPresenter(UserData userData, Picasso picasso) {
    this.userData = userData;
    this.picasso = picasso;
 }

 @Override
 public void attachView(RegistrationView view) {
    super.attachView(view);
    view.toggleKeyboardButton(false);
    view.showFirstName(userData.getFirstName());
    view.showLastName(userData.getLastName());
    view.showEmail(userData.getEmail());
    setImage();
 }

 private void setImage() {
    String url = String.format(IMAGE_URL, userData.getId());
    String tag = String.format(JPG_EXT, userData.getId());
    picasso
            .load(url)
            .tag(tag)
            .into(new Target() {
                @Override
                public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom from) {
                    //some actions
                }

                @Override
                public void onBitmapFailed(Drawable errorDrawable) {
                }

                @Override
                public void onPrepareLoad(Drawable placeHolderDrawable) {
                }

            });
}

在我的演示者中，我通过 Dagger2 提供了 picasso

@Provides
@Singleton
Picasso providesPicasso() {
    return Picasso.with(context);
}

在我的测试中，我使用了 Robolectric 和 Mockito，所以我模拟了 Picasso 并将其传递给演示者的构造函数

@Mock
Picasso picasso;

@Before
public void setUp() {
    super.setUp();
    MockitoAnnotations.initMocks(this);
    mockData = new UserData();
    mockData.setFirstName("Name");
    mockData.setLastName("LastName");
    mockData.setEmail("example@gmail.com");
    mockData.setId("123456");

    File mockCacheDir = mock(File.class);
    Context mockAppContext = mock(Context.class);
    when(mockContext.getApplicationContext()).thenReturn(mockAppContext);
    when(mockContext.getApplicationContext().getCacheDir()).thenReturn(mockCacheDir);
    when(view.getContext()).thenReturn(mockContext);
    presenter = new RegistrationPresenter(mockData, picasso);
}

@Test
public void testAttachView() {
    presenter.attachView(view); //fails here
    verify(view).toggleKeyboardButton(false);
    verify(view).showFirstName(mockData.getFirstName());
    verify(view).showLastName(mockData.getLastName());
    verify(view).showEmail(mockData.getEmail());
}

当我运行我的测试时，它因异常而失败

java.lang.NullPointerException
at com.squareup.picasso.Utils.createDefaultCacheDir(Utils.java:257)
at com.squareup.picasso.OkHttpDownloader.<init>(OkHttpDownloader.java:45)
at com.squareup.picasso.Utils$OkHttpLoaderCreator.create(Utils.java:424)
at com.squareup.picasso.Utils.createDefaultDownloader(Utils.java:250)
at com.squareup.picasso.Picasso$Builder.build(Picasso.java:832)
at com.squareup.picasso.Picasso.with(Picasso.java:662)

模仿 picasso 的正确方法是什么？

Answer 1

Don't mock File.您的测试很可能失败，因为需要真正的 File 实现。而是使用 TemporaryFolder规则:

@Rule
public TemporaryFolder folder = new TemporaryFolder();

@Before
public void setUp() {
  // ...
  when(mockContext.getApplicationContext().getCacheDir()).thenReturn(folder.newFolder()));
  // ...
 }