@VisibleForTesting
    AdminUserDO validateUserExists(Long id) {
        if (id == null) {
            return null;
        }
        AdminUserDO user = userMapper.selectById(id);
        if (user == null) {
            throw exception(USER_NOT_EXISTS);
        }
        return user;
    }
@Test
    public void testValidateUserExists_notExists() {
        assertServiceException(() -> userService.validateUserExists(randomLongId()), USER_NOT_EXISTS);
    }