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

        return AuthFindDto.FindUsernameRes.of(user);
    }
@DisplayName("휴대폰 번호를 통해 유저를 찾아 User를 반환한다.")
    @Test
    void findUsernameIfUserFound() {
        // given
        String phone = "010-1234-5678";
        String username = "jayang";
        User user = UserFixture.GENERAL_USER.toUser();
        given(userService.readUserByPhone(phone)).willReturn(Optional.of(user));

        // when
        AuthFindDto.FindUsernameRes result = authFindService.findUsername(phone);

        // then
        assertEquals(result, new AuthFindDto.FindUsernameRes(username));
    }