@Transactional(readOnly = true)
    public AuthFindDto.FindUsernameRes findUsername(String phone) {
        User user = readGeneralSignUpUser(phone);

        return AuthFindDto.FindUsernameRes.of(user);
    }
@DisplayName("휴대폰 번호로 유저를 찾을 수 없을 때 AuthFinderException을 발생시킨다.")
    @Test
    void findUsernameIfUserNotFound() {
        // given
        String phone = "010-1234-5678";
        given(userService.readUserByPhone(phone)).willReturn(Optional.empty());

        // when - then
        UserErrorException exception = assertThrows(UserErrorException.class, () -> authFindService.findUsername(phone));
        log.debug(exception.getExplainError());
    }