MockMvc not working for DataIntegrityViolationException - spring

Question

We Spring developers know that if one tries to delete an entity that has other associated entities, a DataIntegrityViolationException is thrown.
I wrote a delete method catching both EmptyResultDataAccessException and DataIntegrityViolationException exceptions, throwing custom service-level exceptions for each case:
#Service
public class CityService {
#Autowired
private CityRepository repository;
public void delete(Long id) {
try {
repository.deleteById(id); // returns 204
}
catch (EmptyResultDataAccessException e) {
throw new ResourceNotFoundException("Id not found " + id); // returns 404
}
catch (DataIntegrityViolationException e) {
throw new DatabaseException("Integrity violation"); // returns 400
}
}
}
I've set all up so the first scenario returns 204, the second scenario returns 404, and the third scenario returns 400. Everything is working fine when I test it on Postman.
However, when I try to write an integrated test using MockMvc, the DataIntegrityViolationException scenario doesn't work! (the other two scenarios work).
#SpringBootTest
#AutoConfigureMockMvc
#Transactional
public class CityControllerIT {
#Autowired
private MockMvc mockMvc;
(...)
#Test
public void deleteShouldReturnBadRequestEventWhenDependentId() throws Exception {
mockMvc.perform(delete("/cities/{id}", 1L))
.andExpect(status().isBadRequest());
}
}
It's returning 204 instead of 400! I have printed some messages inside the try block and I have found that it is really not throwing an exception. The try block executes entirely, as there was no integrity violation.
#Service
public class CityService {
#Autowired
private CityRepository repository;
public void delete(Long id) {
try {
System.out.println("START");
repository.deleteById(id);
System.out.println("FINISH");
}
(...)
I am missing something about MockMvc fundamentals? Why integrity violation is being ignored when executing that MockMvc test?
I've saved a minimum-H2-just-clone-and-run project on Github:
https://github.com/acenelio/mockmvc-dataintegrity

Answer 1

DataIntegrityViolationException does NOT work properly with #Transactional, even in a common service method like:
#Service
public class MyService {
#Autowired
private MyRepository repository;
#Transactional
public void delete(Long id) {
try {
repository.deleteById(id);
}
catch (DataIntegrityViolationException e) {
// do something
}
}
}
Similarly, if you want to automate test a DataIntegrityViolationException scenario, you should NOT annotate your test class with #Transactional.
So if your writing transactional integrated tests (which rollback database for each test), you may want to create another test class without #Transactional annotation to test your DataIntegrityViolationException scenario.