如何在安卓的单元测试中模拟毕加索

Question

我有使用毕加索库的代码。

 @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) {
                }
            });
}

在我的演讲者中，我通过Dagger2提供毕加索

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

在我的测试中，我使用的是Robolectric和Mockito，所以我模拟毕加索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("[e-mail]");
    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());
}

当我运行测试时，它失败并出现异常

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)

嘲笑毕加索的正确方法是什么？

Answer 1

不要嘲笑File .您的测试很可能失败，因为需要真正的File实现。请改用临时文件夹规则：

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