### Question:
UserServiceImpl implements UserService { @Override public UserEntity login(LoginReq loginReq) { checkParam(loginReq); UserQueryReq userQueryReq = buildUserQueryReq(loginReq); List<UserEntity> userEntityList = userDAO.findUsers(userQueryReq); if (CollectionUtils.isEmpty(userEntityList)) { throw new CommonBizException(ExpCodeEnum.LOGIN_FAIL); } return userEntityList.get(0); }  @Override UserEntity login(LoginReq loginReq); @Override List<UserEntity> findUsers(UserQueryReq userQueryReq); @Override UserEntity register(RegisterReq registerReq); @Override void batchUpdateUserState(BatchReq<UserStateReq> userStateReqs); @Override void createAdminUser(AdminCreateReq adminCreateReq); @Override List<RoleEntity> findRoles(); @Override void deleteRole(String roleId); @Override void updateMenuOfRole(RoleMenuReq roleMenuReq); @Override void updatePermissionOfRole(RolePermissionReq rolePermissionReq); @Override List<PermissionEntity> findPermissions(); @Override List<MenuEntity> findMenus(); @Override List<LocationEntity> findLocations(String userId); @Override String createLocation(LocationCreateReq locationCreateReq, String userId); @Override void deleteLocation(String locationId, String userId); @Override void modifyLocation(LocationUpdateReq locationUpdateReq, String userId);  }### Answer:
@Test public void login() throws Exception { LoginReq loginReq = new LoginReq(); loginReq.setUsername("chai"); loginReq.setPassword("123"); UserEntity userEntity = userService.login(loginReq); System.out.println(userEntity); }