test: 동시요청 비관적 락 적용, 미적용 최대참가자 초과 테스트 작성 (#116)

* test: 동시요청 락 미적용 최대참가자 초과 테스트 작성

* test: 동시요청 비관적 락 적용 최대참가자 초과 테스트 작성

* style: 기타 코드스타일 적용 누락 수정

Author: Ji-minhyeok

build.gradle

@@ -43,6 +43,8 @@ dependencies {
     testAnnotationProcessor 'org.projectlombok:lombok'
     testImplementation 'org.springframework.boot:spring-boot-starter-test'
     testImplementation 'org.springframework.security:spring-security-test'
+    testImplementation("org.junit.jupiter:junit-jupiter:5.10.0")
+    testRuntimeOnly("org.junit.platform:junit-platform-launcher")
     testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 }
 

src/main/java/com/threestar/trainus/domain/lesson/student/service/StudentLessonService.java

@@ -195,6 +195,57 @@ public LessonApplicationResponseDto applyToLesson(Long lessonId, Long userId) {
 		}
 	}
 
+	@Transactional
+	public LessonApplicationResponseDto applyToLessonWithLock(Long lessonId, Long userId) {
+		Lesson lesson = adminLessonService.findLessonByIdWithLock(lessonId); // 락적용 find 메서드
+
+		User user = userService.getUserById(userId);
+
+		if (lesson.getLessonLeader().equals(userId)) {
+			throw new BusinessException(ErrorCode.LESSON_CREATOR_CANNOT_APPLY);
+		}
+
+		boolean alreadyParticipated = lessonParticipantRepository.existsByLessonIdAndUserId(lessonId, userId);
+		boolean alreadyApplied = lessonApplicationRepository.existsByLessonIdAndUserId(lessonId, userId);
+		if (alreadyParticipated || alreadyApplied) {
+			throw new BusinessException(ErrorCode.ALREADY_APPLIED);
+		}
+
+		if (lesson.getStatus() != LessonStatus.RECRUITING) {
+			throw new BusinessException(ErrorCode.LESSON_NOT_AVAILABLE);
+		}
+
+		if (lesson.getOpenRun()) {
+			LessonParticipant participant = LessonParticipant.builder()
+				.lesson(lesson)
+				.user(user)
+				.build();
+			lessonParticipantRepository.save(participant);
+			lesson.incrementParticipantCount(); // 비관적 락 덕분에 안전하게 증가
+
+			return LessonApplyMapper.toLessonApplicationResponseDto(
+				lesson.getId(),
+				user.getId(),
+				ApplicationStatus.APPROVED,
+				participant.getJoinAt()
+			);
+		} else {
+			LessonApplication application = LessonApplication.builder()
+				.lesson(lesson)
+				.user(user)
+				.build();
+			lessonApplicationRepository.save(application);
+
+			return LessonApplyMapper.toLessonApplicationResponseDto(
+				lesson.getId(),
+				user.getId(),
+				ApplicationStatus.PENDING,
+				application.getCreatedAt()
+			);
+		}
+	}
+
+
 	@Transactional
 	public void cancelLessonApplication(Long lessonId, Long userId) {
 		// 레슨 조회

src/main/java/com/threestar/trainus/domain/lesson/teacher/controller/LocationCsvController.java

@@ -40,4 +40,4 @@ public ResponseEntity<Boolean> checkExists(
 		boolean exists = locationCsvService.checkLocation(city, district, dong, ri);
 		return ResponseEntity.ok(exists);
 	}
-}
+}

src/main/java/com/threestar/trainus/domain/lesson/teacher/entity/Location.java

@@ -31,4 +31,4 @@ public Location(String city, String district, String dong, String ri) {
 		this.dong = dong;
 		this.ri = ri;
 	}
-}
+}

src/main/java/com/threestar/trainus/domain/lesson/teacher/repository/LessonParticipantRepository.java

@@ -1,10 +1,21 @@
 package com.threestar.trainus.domain.lesson.teacher.repository;
 
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.CrudRepository;
 
 import com.threestar.trainus.domain.lesson.teacher.entity.LessonParticipant;
 
+import jakarta.transaction.Transactional;
+
 public interface LessonParticipantRepository extends CrudRepository<LessonParticipant, Long> {
 
 	boolean existsByLessonIdAndUserId(Long lessonId, Long userId);
+
+	long countByLessonId(Long lessonId);
+
+	@Modifying
+	@Transactional
+	@Query("DELETE FROM LessonParticipant lp WHERE lp.lesson.id = :lessonId")
+	void deleteByLessonId(Long lessonId);
 }

src/main/java/com/threestar/trainus/domain/lesson/teacher/repository/LessonRepository.java

@@ -6,13 +6,16 @@
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Lock;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;
 
 import com.threestar.trainus.domain.lesson.teacher.entity.Category;
 import com.threestar.trainus.domain.lesson.teacher.entity.Lesson;
 import com.threestar.trainus.domain.lesson.teacher.entity.LessonStatus;
 
+import jakarta.persistence.LockModeType;
+
 public interface LessonRepository extends JpaRepository<Lesson, Long> {
 	//삭제되지 않은 레슨만 조회
 	Optional<Lesson> findByIdAndDeletedAtIsNull(Long lessonId);
@@ -83,4 +86,8 @@ Page<Lesson> findBySearchConditions(
 		@Param("search") String search,
 		Pageable pageable
 	);
+
+	@Lock(LockModeType.PESSIMISTIC_WRITE) // 비관적 락 적용
+	@Query("SELECT l FROM Lesson l WHERE l.id = :lessonId")
+	Optional<Lesson> findByIdWithLock(@Param("lessonId") Long lessonId);
 }

src/main/java/com/threestar/trainus/domain/lesson/teacher/repository/LocationRepository.java

@@ -8,4 +8,4 @@ public interface LocationRepository extends JpaRepository<Location, Long> {
 	boolean existsByCityAndDistrictAndDongAndRi(String city, String district, String dong, String ri);
 
 	boolean existsByCityAndDistrictAndDong(String city, String district, String dong);
-}
+}

src/main/java/com/threestar/trainus/domain/lesson/teacher/service/AdminLessonService.java

@@ -336,27 +336,32 @@ public Lesson findLessonById(Long lessonId) {
 			.orElseThrow(() -> new BusinessException(ErrorCode.LESSON_NOT_FOUND));
 	}
 
+	public Lesson findLessonByIdWithLock(Long lessonId) {
+		return lessonRepository.findByIdWithLock(lessonId)
+			.orElseThrow(() -> new BusinessException(ErrorCode.LESSON_NOT_FOUND));
+	}
 	//레슨 application조회 및 검증
+
 	public LessonApplication findApplicationById(Long applicationId) {
 		return lessonApplicationRepository.findById(applicationId)
 			.orElseThrow(() -> new BusinessException(ErrorCode.LESSON_APPLICATION_NOT_FOUND));
 	}
-
 	//강사 권한 검증
+
 	public void validateIsYourLesson(Lesson lesson, Long userId) {
 		if (!lesson.getLessonLeader().equals(userId)) {
 			throw new BusinessException(ErrorCode.LESSON_ACCESS_FORBIDDEN);
 		}
 	}
-
 	//레슨 삭제 여부 검증
+
 	public void validateLessonNotDeleted(Lesson lesson) {
 		if (lesson.isDeleted()) {
 			throw new BusinessException(ErrorCode.LESSON_NOT_FOUND);
 		}
 	}
-
 	//레슨 접근 권한 검증 -> 올린사람(강사)가 맞는지 체크
+
 	private Lesson validateLessonAccess(Long lessonId, Long userId) {
 		// User 존재 확인
 		User user = userService.getUserById(userId);
@@ -372,8 +377,8 @@ private Lesson validateLessonAccess(Long lessonId, Long userId) {
 
 		return lesson;
 	}
-
 	//레슨 상태 검증
+
 	private ApplicationStatus validateStatus(String status) {
 		if ("ALL".equals(status)) {
 			return null; // ALL인 경우 null 반환해서 필터링 안함
@@ -385,17 +390,17 @@ private ApplicationStatus validateStatus(String status) {
 			throw new BusinessException(ErrorCode.INVALID_APPLICATION_STATUS);
 		}
 	}
-
 	//레슨 신청 상태 검증
+
 	private LessonStatus validateLessonStatus(String status) {
 		try {
 			return LessonStatus.valueOf(status);
 		} catch (IllegalArgumentException e) {
 			throw new BusinessException(ErrorCode.INVALID_LESSON_STATUS);
 		}
 	}
-
 	//참가자가 있을때 수정 검증
+
 	private void validatePeopleInLessonUpdate(Lesson lesson, LessonUpdateRequestDto requestDto) {
 		// 카테고리 변경 불가
 		if (!lesson.getCategory().equals(requestDto.category())) {
@@ -428,8 +433,8 @@ private void validatePeopleInLessonUpdate(Lesson lesson, LessonUpdateRequestDto
 			throw new BusinessException(ErrorCode.LESSON_PARTICIPANTS_EXIST_RESTRICTION);
 		}
 	}
-
 	//레슨 이미지 업데이트
+
 	private List<LessonImage> updateLessonImages(Lesson lesson, List<String> imageUrls) {
 		// 기존 이미지 삭제
 		List<LessonImage> existingImages = lessonImageRepository.findByLesson(lesson);
@@ -449,14 +454,14 @@ private List<LessonImage> updateLessonImages(Lesson lesson, List<String> imageUr
 
 		return lessonImageRepository.saveAll(newImages);
 	}
-
 	//기본 정보 수정
+
 	private void updateBasicInfo(Lesson lesson, LessonUpdateRequestDto requestDto) {
 		lesson.updateLessonName(requestDto.lessonName());
 		lesson.updateDescription(requestDto.description());
 	}
-
 	//제한되어 있는 필드 수정
+
 	private void updateRestrictedFields(Lesson lesson, LessonUpdateRequestDto requestDto, Long userId, Long lessonId) {
 		// 시간 관련 검증
 		if (requestDto.hasTimeChanges()) {
@@ -483,8 +488,8 @@ private void updateRestrictedFields(Lesson lesson, LessonUpdateRequestDto reques
 		lesson.updateLocation(requestDto.city(), requestDto.district(), requestDto.dong());
 		lesson.updateAddressDetail(requestDto.addressDetail());
 	}
-
 	//레슨 이미지 수정
+
 	private List<LessonImage> updateLessonImagesIfNeeded(Lesson lesson, List<String> newImageUrls) {
 		if (newImageUrls != null) {
 			// 기존 이미지 삭제

src/main/java/com/threestar/trainus/domain/lesson/teacher/service/LocationCsvService.java

@@ -31,7 +31,7 @@ public void processCsv(MultipartFile file) {
 		List<Location> locations = new ArrayList<>();
 
 		try (Reader reader = new BufferedReader(new InputStreamReader(file.getInputStream()));
-			 CSVReader csvReader = new CSVReaderBuilder(reader).withSkipLines(1).build()) {
+			CSVReader csvReader = new CSVReaderBuilder(reader).withSkipLines(1).build()) {
 
 			String[] row;
 			while ((row = csvReader.readNext()) != null) {

src/main/java/com/threestar/trainus/global/config/SwaggerConfig.java

@@ -3,16 +3,16 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 
+import io.swagger.v3.oas.models.Components;
 import io.swagger.v3.oas.models.OpenAPI;
 import io.swagger.v3.oas.models.info.Info;
 import io.swagger.v3.oas.models.security.SecurityRequirement;
 import io.swagger.v3.oas.models.security.SecurityScheme;
-import io.swagger.v3.oas.models.Components;
 
 @Configuration
 public class SwaggerConfig {
 	@Bean
-	public OpenAPI openAPI() {
+	public OpenAPI openApi() {
 		return new OpenAPI()
 			.addSecurityItem(new SecurityRequirement().addList("session"))
 			.components(new Components()
@@ -31,4 +31,4 @@ private Info apiInfo() {
 			.description("운동 메이트 매칭 플랫폼의 API 명세서") // API에 대한 설명
 			.version("1.0.0"); // API의 버전
 	}
-}
+}