Integration Testing for manual Spring Security Login

Question

I am trying to do an integration test for my manual Spring Security Login. Below is the test class:

@RunWith(SpringRunner.class)
@ContextConfiguration
@WebAppConfiguration
@SpringBootTest
@DirtiesContext(methodMode = DirtiesContext.MethodMode.AFTER_METHOD)
class UserIT {


    private MockMvc mockMvc;

    @Autowired
    private ObjectMapper objectMapper;

    @Autowired
    private UserService userService;

    @Autowired
    private WebApplicationContext context;

    @Autowired
    private TestRestTemplate restTemplate;

    @LocalServerPort
    private int port;

    UserDTO userDTO = new UserDTO();
    String username = "user";
    Authorities userAuthorities = new Authorities();
    Set<Authorities> grantedAuthorities = new HashSet<>();

    @BeforeEach
    void setup() {

        mockMvc = MockMvcBuilders
                .webAppContextSetup(context)
                .apply(springSecurity())
                .build();

        userDTO.setUsername(username);
        userDTO.setPassword(username);

        userAuthorities.setUsername(username);
        userAuthorities.setAuthority("ROLE_USER");
        grantedAuthorities.add(userAuthorities);
        userDTO.setAuthorities(grantedAuthorities);


    }

    @Test
    void userLogin() throws Exception {

        mockMvc.perform(post("/user/register/")
                .contentType("application/json")
                .content(objectMapper.writeValueAsString(userDTO)))
                .andExpect(status().isOk());

        mockMvc.perform(post("/user/login/")
                .contentType("application/json")
                .content(objectMapper.writeValueAsString(userDTO)))
                .andExpect(status().isOk());

        Collection<GrantedAuthority> authorities = new HashSet<>();
        SimpleGrantedAuthority simpleGrantedAuthority = new SimpleGrantedAuthority("ROLE_USER");
        authorities.add(simpleGrantedAuthority);

        MvcResult mvcResult = mockMvc.perform(get("/user/authority/")
                .contentType("application/json"))
                .andReturn();


        assertEquals(authorities, mvcResult.getResponse().getContentAsString());
    }

}

The issue is that mvcResult.getResponse().getContentAsString() returns a collection of ROLE_ANONYMOUS instead of ROLE_USER, since I am calling the login endpoint with a ROLE_USER authority user.

Below is my UserService class:

@Service
@AllArgsConstructor
public class UserServiceImpl implements UserService {
    private final UserRepository userRepository;
    private final AuthenticationManager authenticationManager;

    public UserDetails loadUserByUsername(String username){
        Users user = userRepository.findByUsername(username);
        if (user == null)
            throw new UsernameNotFoundException("Username Not Found");

        UserDetails springUser =
                org.springframework.security.core.userdetails.User.builder()
                .authorities(this.getAuthorities(user))
                .username(username)
                .password(user.getPassword())
                .build();

        return springUser;
    }

    public Collection<? extends GrantedAuthority> getAuthoritiesFromContext(){
        Collection<SimpleGrantedAuthority> authorities = (Collection<SimpleGrantedAuthority>)
                SecurityContextHolder.getContext().getAuthentication().getAuthorities();
        return authorities;
    }

    public Collection<? extends GrantedAuthority> getAuthorities(Users user){
        Collection<SimpleGrantedAuthority> authorities = new ArrayList<>();
        user.getAuthorities().forEach(authority ->
                authorities.add(new SimpleGrantedAuthority(authority.getAuthority())));
        return authorities;
    }

    public Users saveUser(UserDTO userDTO){
        Users user = new Users(userDTO.getUsername(), userDTO.getPassword(),
                userDTO.getAuthorities());
        return userRepository.save(user);
    }

    public UserDetails login(UserDTO userDTO){
        UserDetails userDetails = this.loadUserByUsername(userDTO.getUsername());
        if(userDetails.getPassword().equals(userDTO.getPassword())){
            Authentication authentication =
                    new UsernamePasswordAuthenticationToken(userDetails.getUsername(), userDTO.getPassword(), userDetails.getAuthorities());

            authentication = authenticationManager.authenticate(authentication);
            SecurityContextHolder.getContext().setAuthentication(authentication);
            return userDetails;
        } else {
            throw new BadCredentialsException("Username and password do not match!");
        }
    }

}

When I try calling the endpoints through Postman it all works correctly, however in the test, somehow the SecurityContext gets lost and returns ROLE_ANONYMOUS instead of ROLE_USER. Am I missing some annotation in the test class, or is it just that I cannot do an integration test for my manual login?

Thanks in advance!!