Spring/Mockito Junit testing Null Pointer Exception - spring

Question

Trying to get JUnit with mockito testing to work and getting a NPE on my test here. I'm wanting to have a verify that when createRegistrant(registrationDTO) is called, saveUpdateRegistration(Registration reg) method is called right after. An issue I find strange is that on Mockito.verify(registrationServiceImpl, Mockito.times(1)).createRegistrant(registrationDTO); it is not suggesting I can test if saveUpdateRegistration(Registration reg) method was called? IntelliJ only suggests methods that are in my interface?
My test code below:
#RunWith(MockitoJUnitRunner.class)
public class RegistrationServiceImplTest {
#InjectMocks
private RegistrationServiceImpl registrationServiceImpl;
#Mock
private RegistrationDTO registrationDTO;
#Mock
private Registration registration;
#Before
public void setup() {
registrationDTO.seteId("abc123");
registrationDTO.setTech("AWS");
registrationDTO.setFirstName("Bob");
registrationDTO.setLastName("Tom");
}
#Test
public void createRegistrant() throws Exception {
// Mockito.when(registrationServiceImpl.createRegistrant(registrationDTO)).thenReturn(registrationDTO);
Mockito.when(registrationServiceImpl.createRegistrant(registrationDTO)).thenReturn(registrationDTO);
registrationServiceImpl.createRegistrant(registrationDTO);
Mockito.verify(registrationServiceImpl, Mockito.times(1)).createRegistrant(registrationDTO);
}
Here is the code I'm testing:
package com.TechODex.service;
import com.TechODex.dto.RegistrationDTO;
import com.TechODex.model.Registration;
import com.TechODex.dao.RegistrationDAO;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import java.util.List;
#Service
#Transactional
public class RegistrationServiceImpl implements RegistrationService {
#Autowired
private RegistrationDAO registrationDAO;
public RegistrationDTO createRegistrant(RegistrationDTO reg) {
saveUpdateRegistration(setDTOToModel(reg));
return reg;
}
public void deleteRegistrant(Long id) { deleteUserRegistrant(id); }
public List<Registration> findAllRegistrant(String tech) { return findAllRegistrantDAO(tech);}
public List<Registration> findAllTech() { return findAllTechDAO();}
private Registration setDTOToModel(RegistrationDTO dto){
Registration registration = new Registration();
registration.setFirstName(dto.getFirstName());
registration.setLastName(dto.getLastName());
registration.seteId(dto.geteId());
registration.setTech(dto.getTech());
return registration;
}
private void saveUpdateRegistration(Registration reg){ registrationDAO.save(reg);}
}

Answer 1

There are several issues here.
First, you do not mock RegistrationDAO. This will lead to it being null in the class under test. Next, RegistrationService is not a mock, yet you try to use when and verifyon it. Last, RegistrationDTO is mocked, so the invocations to the setters in #Before has no effect.
Your test should look something like:
#RunWith(MockitoJUnitRunner.class)
public class RegistrationServiceImplTest {
#InjectMocks
private RegistrationServiceImpl registrationServiceImpl;
#Mock
private RegistrationDAO registrationDAO;
private RegistrationDTO registrationDTO;
private Registration registration;
#Before
public void setup() {
registration = new Registration();
registration.seteId("abc123");
registration.setTech("AWS");
registration.setFirstName("Bob");
registration.setLastName("Tom");
registrationDTO = new RegistrationDTO();
registrationDTO.seteId("abc123");
registrationDTO.setTech("AWS");
registrationDTO.setFirstName("Bob");
registrationDTO.setLastName("Tom");
}
#Test
public void createRegistrant() throws Exception {
final RegistrationDTO result = registrationServiceImpl.createRegistrant(registrationDTO);
assertSame(registrationDTO, result);
verify(registrationDAO).save(eq(registration));
}
}
given that Registration has an implemented equals-method where the fields that are set are compared. If not, you need to use an ArgumentCaptor.