spring inject mock not used

i am trying to inject a mock to be used by a service class that i am testing but the mock does not seem to be used.

public class SpringDataJPARepo{ public void someMethod();// my repo }

i have a service class that i wish to test

  @Service
  public class Service implements IService{

  @Autowired 
  private SpringDataJPARepo repository;

  public String someMethod(){ // repository instance used here }
  }

and i try to write my test cases by mocking the repository and injecting them into the service

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes={ServiceTestConfiguration.class})
public class Test{

@Mock
private SpringDataJPARepo repository;

@Autowired
@InjectMocks
private IService service;

@Before
public void setup(){
MockitoAnnotations.initMocks(this);
when(repository.someMethod()).thenReturn("test");
}

@Test
public testSomeMethod(){
assertThat(service.someMethod()).isNotNull;
verify(repository.someMethod,atLeast(1)); //fails here
}

}

it throws a

Wanted but not invoked

in the verify method

i am not sure on how to inject the mock into the autowired instance. can anyone point out what i am doing wrong here?