[DP-309] 사용자 프로필 recentAnswers 동일 게시글 중복 표시 버그 수정

src/main/java/com/devpick/domain/user/dto/PublicUserProfileResponse.java

@@ -9,8 +9,10 @@
 
 import java.time.Instant;
 import java.time.ZoneOffset;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.UUID;
+import java.util.stream.Collectors;
 
 public record PublicUserProfileResponse(
         UUID userId,
@@ -50,11 +52,16 @@ public static PublicUserProfileResponse of(
                                 p.getCreatedAt() != null ? p.getCreatedAt().toInstant(ZoneOffset.UTC) : null))
                         .toList(),
                 answers.stream()
-                        .map(a -> new RecentAnswer(
-                                a.getId(),
-                                a.getPost().getId(),
-                                a.getPost().getTitle(),
-                                a.getCreatedAt() != null ? a.getCreatedAt().toInstant(ZoneOffset.UTC) : null))
+                        .collect(Collectors.toMap(
+                                a -> a.getPost().getId(),
+                                a -> new RecentAnswer(
+                                        a.getId(),
+                                        a.getPost().getId(),
+                                        a.getPost().getTitle(),
+                                        a.getCreatedAt() != null ? a.getCreatedAt().toInstant(ZoneOffset.UTC) : null),
+                                (existing, replacement) -> existing,  // 가장 최신 답변 유지 (쿼리가 createdAt DESC 순)
+                                LinkedHashMap::new))
+                        .values().stream()
                         .toList()
         );
     }

src/test/java/com/devpick/domain/user/service/UserServiceTest.java

@@ -145,6 +145,41 @@ void getPublicProfile_withCreatedAt_convertsToInstant() {
         assertThat(response.recentAnswers().get(0).createdAt()).isNotNull();
     }
 
+    @Test
+    @DisplayName("getPublicProfile — 동일 게시글에 답변 여러 개일 때 recentAnswers에 게시글 1개만 포함")
+    void getPublicProfile_multipleAnswersOnSamePost_deduplicatesRecentAnswers() {
+        Post post = Post.builder().user(user).title("Spring 질문").content("내용").level(Level.JUNIOR).build();
+
+        Answer answer1 = Mockito.mock(Answer.class);
+        Answer answer2 = Mockito.mock(Answer.class);
+        UUID postId = UUID.randomUUID();
+        UUID answer1Id = UUID.randomUUID();
+        UUID answer2Id = UUID.randomUUID();
+
+        Post mockPost = Mockito.mock(Post.class);
+        Mockito.when(mockPost.getId()).thenReturn(postId);
+        Mockito.when(mockPost.getTitle()).thenReturn("Spring 질문");
+
+        Mockito.when(answer1.getId()).thenReturn(answer1Id);
+        Mockito.when(answer1.getPost()).thenReturn(mockPost);
+        Mockito.when(answer1.getCreatedAt()).thenReturn(null);
+
+        Mockito.when(answer2.getId()).thenReturn(answer2Id);
+        Mockito.when(answer2.getPost()).thenReturn(mockPost);
+        Mockito.when(answer2.getCreatedAt()).thenReturn(null);
+
+        given(userRepository.findByIdAndIsActiveTrue(userId)).willReturn(Optional.of(user));
+        given(userBadgeRepository.findByUser_IdOrderByAcquiredAtDesc(userId)).willReturn(List.of());
+        given(postRepository.findByUser_IdOrderByCreatedAtDesc(userId)).willReturn(List.of(post));
+        given(answerRepository.findByUserIdWithPost(userId)).willReturn(List.of(answer1, answer2));
+
+        PublicUserProfileResponse response = userService.getPublicProfile(userId);
+
+        assertThat(response.recentAnswers()).hasSize(1);
+        assertThat(response.recentAnswers().get(0).postId()).isEqualTo(postId);
+        assertThat(response.recentAnswers().get(0).answerId()).isEqualTo(answer1Id); // 첫 번째(최신) 답변 유지
+    }
+
     @Test
     @DisplayName("getPublicProfile — 비활성 사용자 USER_NOT_FOUND 예외")
     void getPublicProfile_inactiveUser_throwsUserNotFound() {