Unable to @InjectMocks on instance of android.app.Activity

[realdadfish]

Given the following code

class LoginActivityTest {
    @Rule
    public MockitoRule mockitoRule = MockitoJUnit.rule();

    @Mock
    SomeClass someClass;

    @Mock
    SomeOtherClass someOtherClass;

    ActivityController<TestLoginActivity> loginActivityActivityController =
            Robolectric.buildActivity(TestLoginActivity.class);

    @InjectMocks
    TestLoginActivity testLoginActivity = loginActivityActivityController.get();


    @Test
    public void testSomething() {}

    public static class TestLoginActivity extends android.app.Activity {
        SomeClass someClass;
        SomeOtherClass someOtherClass;
    }
}

the injection fails with the following error:

Mockito couldn't inject mock dependency on field 'private java.lang.Object android.app.Activity.mInstanceTracker' that is annotated with @InjectMocks in your test, 
because there were multiple matching mocks (i.e. fields annotated with @Mock and having matching type): someClass.
If you have multiple fields of same type in your class under test then consider naming the @Mock fields identically to the respective class under test's fields, so Mockito can match them by name.
	at app//org.junit.runners.ParentRunner$3.evaluate(ParentRunner.java:306)
	at app//org.robolectric.RobolectricTestRunner$HelperTestRunner$1.evaluate(RobolectricTestRunner.java:588)
	at app//org.robolectric.internal.SandboxTestRunner$2.lambda$evaluate$2(SandboxTestRunner.java:290)
	at app//org.robolectric.internal.bytecode.Sandbox.lambda$runOnMainThread$0(Sandbox.java:101)
	at java.base@11.0.20.1/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base@11.0.20.1/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base@11.0.20.1/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base@11.0.20.1/java.lang.Thread.run(Thread.java:829)

Issue here is that Android's android.app.Activity has this mInstanceTracker as private variable that, because it is of type Object, matches every possible mock. I think Mockito's approach to inject things here is a little too greedy; Mockito should not scan library files for injectable fields or - since this is not really detectable - at least have some kind of package filter option / possibility to rule out foreign classes that should not be touched.

[realdadfish]

This is also a regression, since this popped up for us when updating an age-old 2.x version of Mockito to the most recent 5.9.0.