Spying Activity with Mockito in Espresso tests with application using Dagger2 dependencies injection

Question

I am very fresh on using the Dagger 2 in Android application. Currently we have application where the some parts of it is injected as dependencies. However, I cannot spy HomeActivity in our Espresso tests using this piece of code:

@LargeTest
@RunWith(AndroidJUnit4.class)

Public class ConnectionRobotTests {

private HomeRobot homeRobot = new HomeRobot();
private NetworkResults networkResults = new NetworkResults();

HomeActivity object;
SingleActivityFactory<HomeActivity> activityFactory =
    new SingleActivityFactory<HomeActivity>(HomeActivity.class) {
        @Override
        protected HomeActivity create(Intent intent) {
            object = spy(getActivityClassToIntercept());
            return object;
        }
    };

@Rule public ActivityTestRule<HomeActivity> testRule =
    new ActivityTestRule<>(activityFactory, true, true);

@AfterClass
public static void afterTest() {
    User.logout();
    Storage.clearAllPreferences();
}

@Test
public void connectAndDisconnectViaQuickConnect() {
    MockConnectionHelper.mockConnection(testRule);
    networkResults.isServerAvailable();

    homeRobot.connect().isConnectedTo();

    ConnectionResult result = homeRobot.disconnect();
    result.isDisconnected();
}

This the TestAppComponent.class:

@Singleton
@Component(modules = {AndroidSupportInjectionModule.class,  
ActivityBuilder.class, MockAppModule.class})
public interface TestAppComponent extends AppComponent {

   @Component.Builder
   interface Builder {

       @BindsInstance
       Builder application(TestApplication application);
       TestAppComponent build();
    }
}

The MockAppModule.class:

@Module
public class MockAppModule {

    @Singleton
    @Provides
    Gson provideGson() {
        return new Gson();
    }
}

TestApplication.class:

public class TestApplication extends MyApplication {
    @Override
    protected AndroidInjector<? extends DaggerApplication> applicationInjector() {
        return DaggerTestAppComponent.builder().application(this).build();
    }
}

When I run the test I get an error:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.application.android/com.application.android.ui.home.HomeActivity}: java.lang.IllegalArgumentException: No injector factory bound for Class<com.application.android.ui.home.HomeActivity$MockitoMock$1418108435>. Injector factories were bound for supertypes of com.application.android.ui.home.HomeActivity$MockitoMock$1418108435: [com.application.android.ui.home.HomeActivity]. Did you mean to bind an injector factory for the subtype?
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2913)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3048)
at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:78)
at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:108)
at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:68)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1808)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.IllegalArgumentException: No injector factory bound for Class<com.application.android.ui.home.HomeActivity$MockitoMock$1418108435>. Injector factories were bound for supertypes of com.application.android.ui.home.HomeActivity$MockitoMock$1418108435: [com.application.android.ui.home.HomeActivity]. Did you mean to bind an injector factory for the subtype?
at dagger.android.DispatchingAndroidInjector.inject(DispatchingAndroidInjector.java:104)
at dagger.android.AndroidInjection.inject(AndroidInjection.java:59)
at com.application.android.ui.home.HomeActivity.onCreate(HomeActivity.java:96)
at android.app.Activity.performCreate(Activity.java:7136)
at android.app.Activity.performCreate(Activity.java:7127)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1271)
at android.support.test.runner.MonitoringInstrumentation.callActivityOnCreate(MonitoringInstrumentation.java:667)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2893)

Is it something I am missing to add? Or should I approach spying of the HomeActivity differently? I was trying to add Injector factory for the HomeActivity, however it didn't changed anything. Does anybody have some suggestions what should be changed to spy HomeActivity?

Answer 1

The problem with spying on activity is that you can only provide AndroidInjector.Factory for a super class which is in this case HomeActivity, but Mockito creates a sub class HomeActivity$MockitoMock$... during Runtime.

From what i found so far - there is no possible way to create AndroidInjector.Factory for subclasses.

It is possible to mock AndroidInjector.Factory but considered a bad practice by Dagger developers themselves.

UPD : I ended up using Robolectric for testing lifecycle of activities\\services, check if it suits your needs as well.