feat: 멘토 승격 요청 횟수 제한 추가

src/main/java/com/example/solidconnection/common/exception/ErrorCode.java

@@ -1,6 +1,7 @@
 package com.example.solidconnection.common.exception;
 
 import static com.example.solidconnection.application.service.ApplicationSubmissionService.APPLICATION_UPDATE_COUNT_LIMIT;
+import static com.example.solidconnection.mentor.service.MentorApplicationService.MENTOR_APPLICATION_COUNT_LIMIT;
 import static com.example.solidconnection.siteuser.service.MyPageService.MIN_DAYS_BETWEEN_NICKNAME_CHANGES;
 
 import lombok.AllArgsConstructor;
@@ -133,6 +134,7 @@ public enum ErrorCode {
     UNAUTHORIZED_MENTORING(HttpStatus.FORBIDDEN.value(), "멘토링 권한이 없습니다."),
     MENTORING_ALREADY_CONFIRMED(HttpStatus.BAD_REQUEST.value(), "이미 승인 또는 거절된 멘토링입니다."),
     MENTOR_APPLICATION_ALREADY_EXISTED(HttpStatus.CONFLICT.value(), "멘토 승격 요청이 이미 존재합니다."),
+    MENTOR_APPLICATION_LIMIT_EXCEEDED(HttpStatus.BAD_REQUEST.value(), "멘토 승격 요청은 " + MENTOR_APPLICATION_COUNT_LIMIT + "회까지만 가능합니다."),
     INVALID_EXCHANGE_STATUS_FOR_MENTOR(HttpStatus.BAD_REQUEST.value(), "멘토 승격 지원 가능한 교환학생 상태가 아닙니다."),
     UNIVERSITY_ID_REQUIRED_FOR_CATALOG(HttpStatus.BAD_REQUEST.value(), "목록에서 학교를 선택한 경우 학교 정보가 필요합니다."),
     UNIVERSITY_ID_MUST_BE_NULL_FOR_OTHER(HttpStatus.BAD_REQUEST.value(), "기타 학교를 선택한 경우 학교 정보를 입력할 수 없습니다."),

src/main/java/com/example/solidconnection/mentor/service/MentorApplicationService.java

@@ -1,6 +1,7 @@
 package com.example.solidconnection.mentor.service;
 
 import static com.example.solidconnection.common.exception.ErrorCode.MENTOR_APPLICATION_ALREADY_EXISTED;
+import static com.example.solidconnection.common.exception.ErrorCode.MENTOR_APPLICATION_LIMIT_EXCEEDED;
 import static com.example.solidconnection.common.exception.ErrorCode.TERM_NOT_FOUND;
 import static com.example.solidconnection.common.exception.ErrorCode.USER_NOT_FOUND;
 
@@ -28,6 +29,8 @@
 @Slf4j
 public class MentorApplicationService {
 
+    public static final int MENTOR_APPLICATION_COUNT_LIMIT = 5;
+
     private final MentorApplicationRepository mentorApplicationRepository;
     private final SiteUserRepository siteUserRepository;
     private final S3Service s3Service;
@@ -40,6 +43,7 @@ public void submitMentorApplication(
             MultipartFile file
     ) {
         ensureNoPendingOrApprovedMentorApplication(siteUserId);
+        ensureApplicationCountNotExceeded(siteUserId);
 
         SiteUser siteUser = siteUserRepository.findById(siteUserId)
                 .orElseThrow(() -> new CustomException(USER_NOT_FOUND));
@@ -66,4 +70,10 @@ private void ensureNoPendingOrApprovedMentorApplication(long siteUserId) {
             throw new CustomException(MENTOR_APPLICATION_ALREADY_EXISTED);
         }
     }
+
+    private void ensureApplicationCountNotExceeded(long siteUserId) {
+        if (mentorApplicationRepository.countBySiteUserId(siteUserId) >= MENTOR_APPLICATION_COUNT_LIMIT) {
+            throw new CustomException(MENTOR_APPLICATION_LIMIT_EXCEEDED);
+        }
+    }
 }

src/test/java/com/example/solidconnection/mentor/service/MentorApplicationServiceTest.java

@@ -1,8 +1,10 @@
 package com.example.solidconnection.mentor.service;
 
 import static com.example.solidconnection.common.exception.ErrorCode.MENTOR_APPLICATION_ALREADY_EXISTED;
+import static com.example.solidconnection.common.exception.ErrorCode.MENTOR_APPLICATION_LIMIT_EXCEEDED;
 import static com.example.solidconnection.common.exception.ErrorCode.UNIVERSITY_ID_MUST_BE_NULL_FOR_OTHER;
 import static com.example.solidconnection.common.exception.ErrorCode.UNIVERSITY_ID_REQUIRED_FOR_CATALOG;
+import static com.example.solidconnection.mentor.service.MentorApplicationService.MENTOR_APPLICATION_COUNT_LIMIT;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.AssertionsForClassTypes.assertThatCode;
 import static org.mockito.BDDMockito.given;
@@ -163,6 +165,24 @@ void setUp() {
                 .hasMessage(MENTOR_APPLICATION_ALREADY_EXISTED.getMessage());
     }
 
+    @Test
+    void 멘토_승격_신청_횟수가_최대_횟수에_도달하면_예외가_발생한다() {
+        // given
+        for (int i = 0; i < MENTOR_APPLICATION_COUNT_LIMIT; i++) {
+            mentorApplicationFixture.거절된_멘토신청(user.getId(), UniversitySelectType.CATALOG, 1L);
+        }
+
+        UniversitySelectType universitySelectType = UniversitySelectType.CATALOG;
+        Long universityId = 1L;
+        MentorApplicationRequest request = createMentorApplicationRequest(universitySelectType, universityId);
+        MockMultipartFile file = createMentorProofFile();
+
+        // when & then
+        assertThatCode(() -> mentorApplicationService.submitMentorApplication(user.getId(), request, file))
+                .isInstanceOf(CustomException.class)
+                .hasMessage(MENTOR_APPLICATION_LIMIT_EXCEEDED.getMessage());
+    }
+
     @Test
     void 이미_REJECTED_상태인_멘토_승격_요청이_존재할_때_멘토_신청이_등록된다() {
         // given