test: 좋아요 충돌 처리 유틸 검증 추가

Author: pooreumjung

src/main/java/com/semosan/api/domain/mountain/service/CourseLikeService.java

@@ -40,13 +40,13 @@ private boolean toggle(Long userId, Long courseId) {
                     courseLikeRepository.delete(existing);
                     return false;
                 })
-                .orElseGet(() -> createCourseLike(user, course, userId, courseId));
+                .orElseGet(() -> createCourseLike(user, course));
     }
 
-    private boolean createCourseLike(User user, Course course, Long userId, Long courseId) {
+    private boolean createCourseLike(User user, Course course) {
         return LikeConflictHandler.handleConcurrentCreate(
                 () -> courseLikeRepository.save(CourseLike.create(user, course)),
-                () -> log.warn("CourseLike 동시 요청 감지: courseId={}, userId={}", courseId, userId)
+                () -> log.warn("CourseLike 동시 요청 감지: courseId={}, userId={}", course.getId(), user.getId())
         );
     }
 

src/test/java/com/semosan/api/common/util/LikeConflictHandlerTest.java

@@ -0,0 +1,54 @@
+package com.semosan.api.common.util;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.dao.DataIntegrityViolationException;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+class LikeConflictHandlerTest {
+
+    @Test
+    void handleConcurrentCreateReturnsTrueWhenCreateActionSucceeds() {
+        AtomicBoolean createCalled = new AtomicBoolean(false);
+        AtomicBoolean logCalled = new AtomicBoolean(false);
+
+        boolean result = LikeConflictHandler.handleConcurrentCreate(
+                () -> createCalled.set(true),
+                () -> logCalled.set(true)
+        );
+
+        assertThat(result).isTrue();
+        assertThat(createCalled).isTrue();
+        assertThat(logCalled).isFalse();
+    }
+
+    @Test
+    void handleConcurrentCreateReturnsTrueAndRunsLogActionWhenDataIntegrityViolationOccurs() {
+        AtomicBoolean logCalled = new AtomicBoolean(false);
+
+        boolean result = LikeConflictHandler.handleConcurrentCreate(
+                () -> {
+                    throw new DataIntegrityViolationException("duplicate");
+                },
+                () -> logCalled.set(true)
+        );
+
+        assertThat(result).isTrue();
+        assertThat(logCalled).isTrue();
+    }
+
+    @Test
+    void handleConcurrentCreateRethrowsUnexpectedException() {
+        RuntimeException exception = new IllegalStateException("unexpected");
+
+        assertThatThrownBy(() -> LikeConflictHandler.handleConcurrentCreate(
+                () -> {
+                    throw exception;
+                },
+                () -> {}
+        )).isSameAs(exception);
+    }
+}