Retrofit Unit Test with Roboletric - unit-testing

Question

Is there any possibility to test if Retrofit callback return success?
My code is quite simple:
#Config(constants = BuildConfig.class, sdk = 21,
manifest = "app/src/main/AndroidManifest.xml")
#RunWith(RobolectricGradleTestRunner.class)
public class RetrofitCallTest {
private MainActivity mainActivity;
#Mock
private RetrofitApi mockRetrofitApiImpl;
#Captor
private ArgumentCaptor<Callback<List<MyObject>>> callbackArgumentCaptor;
#Before
public void setUp() {
MockitoAnnotations.initMocks(this);
ActivityController<MainActivity> controller = Robolectric.buildActivity(MainActivity.class);
mainActivity = controller.get();
RestClient.setApi(mockRetrofitApiImpl);
controller.create();
}
#Test
public void shouldFillAdapter() throws Exception {
Mockito.verify(mockRetrofitApiImpl)
.getYourObject(callbackAgrumentCaptor.capture());
int objectsQuantity = 10;
List<MyObject> list = new ArrayList<YourObject>;
for(int i = 0; i < objectsQuantity; ++i) {
list.add(new MyObject());
}
callbackArgumentCaptor.getValue().success(list, null);
ListAdapter adapter = mainActivity.getAdapter();
assertThat(adapter .getItemCount(), equalTo(objectsQuantity));
}
It's clear - I test if my code works correctly WHEN api return success.
But is there any posibility to test IF api return success?