public abstract class ResourceController<T extends RESTResource<T>> extends MainController {

        @Autowired
        protected RESTRepository<T> itemRepository;

        public Page<T> listAll(T search, Pageable pageable) {
            return itemRepository.findAll(search, pageable);
        }
    }

@NoRepositoryBean
    public interface RESTRepository<T> extends PagingAndSortingRepository<T,
    String>, JpaSpecificationExecutor<T> {

    }

@RunWith(SpringRunner.class)
    @ContextConfiguration
    public class ResourceControllerTest {



        @MockBean(classes = ResourceController.class, answer = CALLS_REAL_METHODS)
        private  ResourceController ressourceControler;

        @MockBean(classes = RESTResource.class)
        private  RESTResource search;

        @MockBean
        protected RESTRepository itemRepository;

        @MockBean
        private Pageable pageable;

        @Before
        public void initMocks(){
            MockitoAnnotations.initMocks(this);
        }


        @Test
        public void testListAll() throws Exception {

            // Given
            Page page = new PageImpl(new ArrayList());

            when(itemRepository.findAll(search, pageable)).thenReturn(page);

            // When
            Object obj = ressourceControler.listAll(search, pageable);

            //Then
                    ...
        }