详解Android单元测试最佳实践

 testOptions {
  unitTests {
   includeAndroidResources true
  }
 }

 testImplementation 'junit:junit:4.12'
 testImplementation 'org.robolectric:robolectric:3.8'
 testImplementation 'org.robolectric:shadows-supportv4:3.8'
 testImplementation 'org.powermock:powermock-module-junit4:1.6.6'
 testImplementation 'org.powermock:powermock-module-junit4-rule:1.6.6'
 testImplementation 'org.powermock:powermock-api-mockito:1.6.6'
 testImplementation 'org.powermock:powermock-classloading-xstream:1.6.6'
 testImplementation 'org.mockito:mockito-all:1.10.19'

@RunWith(RobolectricTestRunner.class)
@Config(sdk = 21, cOnstants= BuildConfig.class)
@PowerMockIgnore({"org.mockito.*", "org.robolectric.*", "android.*"})
@PrepareForTest({PresenterFactory.class})

 @Before
 public void setUp() {
  appCOntext= RuntimeEnvironment.application.getApplicationContext();
  PowerMockito.mockStatic(PresenterFactory.class);
 }

 @Test
 public void onCreate_text1() {
  MainActivity activity = Robolectric.buildActivity(MainActivity.class).create().get();
  String expect = appContext.getString(R.string.hell_world);
  assertEquals(expect, ((TextView)activity.findViewById(R.id.lbl_text1)).getText());
 }

 @Test
 public void btn1_click() {
  MainActivity activity = Robolectric.setupActivity(MainActivity.class);
  activity.findViewById(R.id.btn_1).performClick();
  String expect = appContext.getString(R.string.hell_world);
  assertEquals(expect, ShadowToast.getTextOfLatestToast());
 }

 @Test
 public void btn2_click() {
  MainContract.Presenter presenter = Mockito.mock(MainContract.Presenter.class);
  PowerMockito.when(PresenterFactory.create(Mockito.any(MainContract.View.class), Mockito.any(AppExecutors.class)))
    .thenReturn(presenter);

  MainActivity activity = Robolectric.setupActivity(MainActivity.class);

  activity.findViewById(R.id.btn_2).performClick();

  Mockito.verify(presenter, Mockito.times(1))
    .fetch();
 }

@RunWith(PowerMockRunner.class)
@PrepareForTest({ServiceFactory.class})

 @Before
 public void setUp() {
  PowerMockito.mockStatic(ServiceFactory.class);
 }

 @Test
 public void fetch_success() {
  String expected = "hello world";
  SlowService service = Mockito.mock(SlowService.class);
  Mockito.when(service.fetch()).thenReturn(expected);
  PowerMockito.when(ServiceFactory.create())
    .thenReturn(service);

  MainContract.View view = Mockito.mock(MainContract.View.class);
  MainPresenter presenter = new MainPresenter(view, executors);

  presenter.fetch();

  Mockito.verify(service, Mockito.times(1)).fetch();
  Mockito.verify(view, Mockito.times(1)).onFetchStarted();
  Mockito.verify(view, Mockito.times(1)).onFetchCompleted();
  Mockito.verify(view, Mockito.times(0)).onFetchFailed(Mockito.anyObject());
  ArgumentCaptor captor = ArgumentCaptor.forClass(String.class);
  Mockito.verify(view, Mockito.times(1)).onFetchSuccess(captor.capture());
  assertEquals(expected, captor.getValue());
 }

 @Test
 public void fetch_failed() {
  RuntimeException exception = new RuntimeException("fetch failed");

  SlowService service = Mockito.mock(SlowService.class);
  Mockito.when(service.fetch()).thenThrow(exception);
  PowerMockito.when(ServiceFactory.create())
    .thenReturn(service);

  MainContract.View view = Mockito.mock(MainContract.View.class);
  MainPresenter presenter = new MainPresenter(view, executors);

  presenter.fetch();

  Mockito.verify(service, Mockito.times(1)).fetch();
  Mockito.verify(view, Mockito.times(1)).onFetchStarted();
  Mockito.verify(view, Mockito.times(1)).onFetchCompleted();
  ArgumentCaptor captor = ArgumentCaptor.forClass(Throwable.class);
  Mockito.verify(view, Mockito.times(1)).onFetchFailed(captor.capture());
  assertEquals(exception, captor.getValue());
  Mockito.verify(view, Mockito.times(0)).onFetchSuccess(Mockito.anyString());
 }

public class SlowServiceImplTest {

 @Test
 public void fetch_data() {
  SlowServiceImpl impl = new SlowServiceImpl();
  String data = impl.fetch();
  assertEquals("from slow service", data);
 }

}

gradlew :app:testDebugUnitTest