AddressRepository.java

@Repository
public class AddressRepository {

    List<Address> findAll() {
        return List.of(new Address("a"), new Address("b"));
    }
}

record Address(String street) {}

AddressRepositoryTest.java

@SpringBootTest
class AddressRepositoryTest {

    @Mock
    private AddressRepository addressRepository;

    @InjectMocks
    private AddressService addressService;

    @BeforeEach
    void setUp() {
        MockitoAnnotations.openMocks(this);
    }

    @Test
    void test() {
        when(addressRepository.findAll()).thenReturn(List.of(new Address("Rua Vergueiro")));

        var all = addressService.findAll();

        System.out.println(all);
        Assertions.assertEquals(1, all.size());
    }
}

AddressService.java

@Service
public class AddressService {

    private final AddressRepository addressRepository;

    public AddressService(AddressRepository addressRepository) {
        this.addressRepository = addressRepository;
    }

    List<Address> findAll() {
        return this.addressRepository.findAll();
    }
}