[fix] fcm token 중복 검증 추가

src/main/java/codesquad/fineants/domain/fcm_token/FcmRepository.java

@@ -1,6 +1,7 @@
 package codesquad.fineants.domain.fcm_token;
 
 import java.util.List;
+import java.util.Optional;
 
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Modifying;
@@ -11,6 +12,9 @@ public interface FcmRepository extends JpaRepository<FcmToken, Long> {
 	@Query("select f from FcmToken f where f.member.id = :memberId")
 	List<FcmToken> findAllByMemberId(@Param("memberId") Long memberId);
 
+	@Query("select f from FcmToken f where f.token = :token and f.member.id = :memberId")
+	Optional<FcmToken> findByToken(@Param("token") String token, @Param("memberId") Long memberId);
+
 	@Modifying
 	@Query("delete from FcmToken f where f.token in (:tokens)")
 	int deleteAllByTokens(@Param("tokens") List<String> tokens);

src/main/java/codesquad/fineants/spring/api/errors/errorcode/FcmErrorCode.java

@@ -9,7 +9,8 @@
 @RequiredArgsConstructor
 public enum FcmErrorCode implements ErrorCode {
 
-	BAD_REQUEST_FCM_TOKEN(HttpStatus.BAD_REQUEST, "유효하지 않은 FCM 토큰입니다");
+	BAD_REQUEST_FCM_TOKEN(HttpStatus.BAD_REQUEST, "유효하지 않은 FCM 토큰입니다"),
+	CONFLICT_FCM_TOKEN(HttpStatus.CONFLICT, "중복된 FCM 토큰입니다");
 
 	private final HttpStatus httpStatus;
 	private final String message;

src/main/java/codesquad/fineants/spring/api/fcm/service/FcmService.java

@@ -16,6 +16,7 @@
 import codesquad.fineants.spring.api.errors.errorcode.FcmErrorCode;
 import codesquad.fineants.spring.api.errors.errorcode.MemberErrorCode;
 import codesquad.fineants.spring.api.errors.exception.BadRequestException;
+import codesquad.fineants.spring.api.errors.exception.ConflictException;
 import codesquad.fineants.spring.api.errors.exception.NotFoundResourceException;
 import codesquad.fineants.spring.api.fcm.request.FcmRegisterRequest;
 import codesquad.fineants.spring.api.fcm.response.FcmDeleteResponse;
@@ -36,6 +37,7 @@ public class FcmService {
 	@Transactional
 	public FcmRegisterResponse registerToken(FcmRegisterRequest request, AuthMember authMember) {
 		Member member = findMember(authMember);
+		verifyUniqueFcmToken(request.getFcmToken(), authMember.getMemberId());
 		verifyFcmToken(request.getFcmToken());
 		FcmToken saveFcmToken = fcmRepository.save(request.toEntity(member));
 		return FcmRegisterResponse.from(saveFcmToken);
@@ -51,6 +53,7 @@ private void verifyFcmToken(String token) {
 			firebaseMessaging.send(message, true);
 		} catch (FirebaseMessagingException e) {
 			log.info(e.getMessage(), e);
+
 			throw new BadRequestException(FcmErrorCode.BAD_REQUEST_FCM_TOKEN);
 		}
 	}
@@ -60,6 +63,12 @@ private Member findMember(AuthMember authMember) {
 			.orElseThrow(() -> new NotFoundResourceException(MemberErrorCode.NOT_FOUND_MEMBER));
 	}
 
+	private void verifyUniqueFcmToken(String fcmToken, Long memberId) {
+		if (fcmRepository.findByToken(fcmToken, memberId).isPresent()) {
+			throw new ConflictException(FcmErrorCode.CONFLICT_FCM_TOKEN);
+		}
+	}
+
 	@Transactional
 	public FcmDeleteResponse deleteToken(Long fcmTokenId) {
 		int deleteCount = fcmRepository.deleteByFcmTokenId(fcmTokenId);

src/test/java/codesquad/fineants/spring/api/fcm/service/FcmServiceTest.java

@@ -4,6 +4,8 @@
 import static org.mockito.ArgumentMatchers.*;
 import static org.mockito.BDDMockito.*;
 
+import java.time.LocalDateTime;
+
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
@@ -17,11 +19,13 @@
 import com.google.firebase.messaging.Message;
 
 import codesquad.fineants.domain.fcm_token.FcmRepository;
+import codesquad.fineants.domain.fcm_token.FcmToken;
 import codesquad.fineants.domain.member.Member;
 import codesquad.fineants.domain.member.MemberRepository;
 import codesquad.fineants.domain.oauth.support.AuthMember;
 import codesquad.fineants.spring.api.errors.errorcode.FcmErrorCode;
 import codesquad.fineants.spring.api.errors.exception.BadRequestException;
+import codesquad.fineants.spring.api.errors.exception.ConflictException;
 import codesquad.fineants.spring.api.fcm.request.FcmRegisterRequest;
 import codesquad.fineants.spring.api.fcm.response.FcmRegisterResponse;
 
@@ -88,6 +92,28 @@ void registerToken_whenInvalidToken_thenThrow400Error() throws FirebaseMessaging
 			.hasMessage(FcmErrorCode.BAD_REQUEST_FCM_TOKEN.getMessage());
 	}
 
+	@DisplayName("사용자는 이미 동일한 FCM 토큰이 존재하면 등록할 수 없다")
+	@Test
+	void registerToken_whenAlreadyFcmToken_thenThrow409Error() {
+		// given
+		Member member = memberRepository.save(createMember());
+		fcmRepository.save(FcmToken.builder()
+			.latestActivationTime(LocalDateTime.now())
+			.token("fcmToken")
+			.member(member)
+			.build());
+		FcmRegisterRequest request = FcmRegisterRequest.builder()
+			.fcmToken("fcmToken")
+			.build();
+		// when
+		Throwable throwable = catchThrowable(() -> fcmService.registerToken(request, AuthMember.from(member)));
+
+		// then
+		assertThat(throwable)
+			.isInstanceOf(ConflictException.class)
+			.hasMessage(FcmErrorCode.CONFLICT_FCM_TOKEN.getMessage());
+	}
+
 	private Member createMember() {
 		return Member.builder()
 			.nickname("nemo1234")