How to properly spy on an Activity

Question

Mockito creates a proxy instance when some thing is spied on. Now, is there any way to forward setters that are then executed on that proxy instance to the real instance tha

Answer 1

Using:

android Test Support library's SingleActivityFactory, ActivityTestRule and Mockito's spy()

dependencies {
  androidTestImplementation 'com.android.support.test:runner:1.0.2'
  androidTestImplementation 'com.android.support.test:rules:1.0.2'
  androidTestImplementation 'org.mockito:mockito-android:2.21.0'
}

Outline:

inject the spied instance inside SingleActivityFactory's implementation

Code:

public class MainActivityTest {
    MainActivity subject;

    SingleActivityFactory activityFactory = new SingleActivityFactory(MainActivity.class) {
        @Override
        protected MainActivity create(Intent intent) {
            subject = spy(getActivityClassToIntercept());
            return subject;
        }
    };

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

    @Test
    public void activity_isBeingSpied() {
        verify(subject).setContentView(R.layout.activity_main);
    }

}