@Transactional
    public String login(OauthLoginRequest request) {
        OauthInfoApiResponse oauthInfoApiResponse = oauthClient.requestOauthInfo(request);

        User user = userRepository.findByEmail(oauthInfoApiResponse.kakao_account().email())
                .orElseGet(() -> signUp(oauthInfoApiResponse));

        return jwtTokenProvider.createToken(user);
    }
@DisplayName("로그인 성공 : 존재하는 회원이면 데이터베이스에 새로운 유저를 추가하지않고 토큰을 바로 반환한다.")
    @Test
    void login() {
        // given
        userRepository.save(USER1);
        Mockito.when(oauthClient.requestOauthInfo(any(OauthLoginRequest.class)))
                .thenReturn(UserFixture.OAUTH_INFO_RESPONSE_USER1);

        // when
        String token = authService.login(oauthLoginRequest);

        // then
        assertThat(token).isNotBlank();
    }