[DP-484] 커뮤니티 본인 답변 채택 버튼 노출 및 채택 허용 버그 수정

src/main/java/com/devpick/domain/community/controller/AnswerController.java

@@ -43,8 +43,9 @@ public class AnswerController {
     })
     @GetMapping
     public ApiResponse<AnswerListResponse> getAnswers(
+            @AuthenticationPrincipal UUID userId,
             @Parameter(description = "게시글 ID (UUID)", required = true) @PathVariable UUID postId) {
-        return ApiResponse.ok(answerService.getAnswers(postId));
+        return ApiResponse.ok(answerService.getAnswers(postId, userId));
     }
 
     @Operation(summary = "답변 작성", description = "게시글에 답변을 작성합니다.")

src/main/java/com/devpick/domain/community/dto/AnswerWithCommentsResponse.java

@@ -20,11 +20,17 @@ public record AnswerWithCommentsResponse(
         String authorProfileImage,
         Boolean isAdopted,
         Boolean isEdited,
+        Boolean canAdopt,
         Instant createdAt,
         Instant updatedAt,
         List<CommentResponse> comments
 ) {
-    public static AnswerWithCommentsResponse of(Answer answer, List<Comment> comments) {
+    public static AnswerWithCommentsResponse of(Answer answer, List<Comment> comments,
+                                                UUID currentUserId, UUID postAuthorId, boolean anyAdopted) {
+        boolean canAdopt = postAuthorId.equals(currentUserId)
+                && !anyAdopted
+                && !Boolean.TRUE.equals(answer.getIsAdopted())
+                && !answer.getUser().getId().equals(currentUserId);
         return new AnswerWithCommentsResponse(
                 answer.getId(),
                 answer.getContent(),
@@ -35,6 +41,7 @@ public static AnswerWithCommentsResponse of(Answer answer, List<Comment> comment
                 answer.getUser().getProfileImage(),
                 answer.getIsAdopted(),
                 answer.getIsEdited(),
+                canAdopt,
                 answer.getCreatedAt() != null ? answer.getCreatedAt().toInstant(ZoneOffset.UTC) : null,
                 answer.getUpdatedAt() != null ? answer.getUpdatedAt().toInstant(ZoneOffset.UTC) : null,
                 comments.stream().map(CommentResponse::of).toList()

src/main/java/com/devpick/domain/community/service/AnswerService.java

@@ -40,15 +40,18 @@ public class AnswerService {
     private final AnswerLikeRepository answerLikeRepository;
 
     @Transactional(readOnly = true)
-    public AnswerListResponse getAnswers(UUID postId) {
-        postRepository.findById(postId)
+    public AnswerListResponse getAnswers(UUID postId, UUID currentUserId) {
+        Post post = postRepository.findById(postId)
                 .orElseThrow(() -> new DevpickException(ErrorCode.COMMUNITY_POST_NOT_FOUND));
 
         List<Answer> answers = answerRepository.findByPost_IdOrderByCreatedAtAsc(postId);
+        boolean anyAdopted = answers.stream().anyMatch(a -> Boolean.TRUE.equals(a.getIsAdopted()));
+        UUID postAuthorId = post.getUser().getId();
+
         List<AnswerWithCommentsResponse> result = answers.stream()
                 .map(answer -> {
                     List<Comment> comments = commentRepository.findByAnswer_IdOrderByCreatedAtAsc(answer.getId());
-                    return AnswerWithCommentsResponse.of(answer, comments);
+                    return AnswerWithCommentsResponse.of(answer, comments, currentUserId, postAuthorId, anyAdopted);
                 })
                 .toList();
         return new AnswerListResponse(result);
@@ -137,6 +140,10 @@ public AnswerResponse adoptAnswer(UUID userId, UUID postId, UUID answerId) {
             throw new DevpickException(ErrorCode.COMMUNITY_ANSWER_NOT_FOUND);
         }
 
+        if (answer.getUser().getId().equals(userId)) {
+            throw new DevpickException(ErrorCode.COMMUNITY_CANNOT_ADOPT_OWN_ANSWER);
+        }
+
         answer.adopt();
         pointService.earn(answer.getUser(), PointAction.ANSWER_ADOPTED);
         return AnswerResponse.of(answer);

src/main/java/com/devpick/global/common/exception/ErrorCode.java

@@ -86,6 +86,7 @@ public enum ErrorCode {
     COMMUNITY_ANSWER_NOT_LIKED(HttpStatus.NOT_FOUND, "COMMUNITY_012", "좋아요하지 않은 답변입니다."),
     COMMUNITY_DUPLICATE_POST(HttpStatus.CONFLICT, "COMMUNITY_013", "잠시 후 다시 시도해 주세요."),
     COMMUNITY_AI_NOT_SUPPORTED(HttpStatus.BAD_REQUEST, "COMMUNITY_014", "커리어 게시글은 AI 기능을 지원하지 않습니다."),
+    COMMUNITY_CANNOT_ADOPT_OWN_ANSWER(HttpStatus.FORBIDDEN, "COMMUNITY_015", "본인이 작성한 답변은 채택할 수 없습니다."),
 
     // Report
     REPORT_NOT_FOUND(HttpStatus.NOT_FOUND, "REPORT_001", "주간 리포트를 찾을 수 없습니다."),

src/test/java/com/devpick/domain/community/controller/AnswerControllerTest.java

@@ -190,28 +190,40 @@ void adoptAnswer_alreadyAdopted_returns409() throws Exception {
     void getAnswers_success_returns200() throws Exception {
         AnswerWithCommentsResponse answerWithComments = new AnswerWithCommentsResponse(
                 answerId, "Test Answer", userId, "tester", null, null, null,
-                false, false, Instant.now(), Instant.now(), List.of()
+                false, false, false, Instant.now(), Instant.now(), List.of()
         );
         AnswerListResponse listResponse = new AnswerListResponse(List.of(answerWithComments));
-        given(answerService.getAnswers(postId)).willReturn(listResponse);
+        given(answerService.getAnswers(postId, userId)).willReturn(listResponse);
 
         mockMvc.perform(org.springframework.test.web.servlet.request.MockMvcRequestBuilders
                         .get("/posts/" + postId + "/answers"))
                 .andExpect(status().isOk())
                 .andExpect(jsonPath("$.success").value(true))
                 .andExpect(jsonPath("$.data.answers[0].content").value("Test Answer"))
-                .andExpect(jsonPath("$.data.answers[0].comments").isArray());
+                .andExpect(jsonPath("$.data.answers[0].comments").isArray())
+                .andExpect(jsonPath("$.data.answers[0].canAdopt").value(false));
     }
 
     @Test
     @DisplayName("GET /posts/{postId}/answers - 게시글 없으면 404 반환")
     void getAnswers_postNotFound_returns404() throws Exception {
-        given(answerService.getAnswers(postId))
+        given(answerService.getAnswers(postId, userId))
                 .willThrow(new DevpickException(ErrorCode.COMMUNITY_POST_NOT_FOUND));
 
         mockMvc.perform(org.springframework.test.web.servlet.request.MockMvcRequestBuilders
                         .get("/posts/" + postId + "/answers"))
                 .andExpect(status().isNotFound())
                 .andExpect(jsonPath("$.success").value(false));
     }
+
+    @Test
+    @DisplayName("POST /posts/{postId}/answers/{answerId}/adopt - 본인 답변 채택 시 403 반환")
+    void adoptAnswer_ownAnswer_returns403() throws Exception {
+        given(answerService.adoptAnswer(userId, postId, answerId))
+                .willThrow(new DevpickException(ErrorCode.COMMUNITY_CANNOT_ADOPT_OWN_ANSWER));
+
+        mockMvc.perform(post("/posts/" + postId + "/answers/" + answerId + "/adopt"))
+                .andExpect(status().isForbidden())
+                .andExpect(jsonPath("$.success").value(false));
+    }
 }

src/test/java/com/devpick/domain/community/service/AnswerServiceTest.java

@@ -108,24 +108,89 @@ void getAnswers_success_returnsAnswerListWithComments() {
         given(answerRepository.findByPost_IdOrderByCreatedAtAsc(postId)).willReturn(List.of(answer));
         given(commentRepository.findByAnswer_IdOrderByCreatedAtAsc(answerId)).willReturn(List.of());
 
-        AnswerListResponse response = answerService.getAnswers(postId);
+        AnswerListResponse response = answerService.getAnswers(postId, userId);
 
         assertThat(response.answers()).hasSize(1);
         assertThat(response.answers().get(0).id()).isEqualTo(answerId);
         assertThat(response.answers().get(0).comments()).isEmpty();
+        assertThat(response.answers().get(0).canAdopt()).isFalse();
     }
 
     @Test
     @DisplayName("getAnswers — 게시글 없으면 COMMUNITY_POST_NOT_FOUND 예외")
     void getAnswers_postNotFound_throwsException() {
         given(postRepository.findById(postId)).willReturn(Optional.empty());
 
-        assertThatThrownBy(() -> answerService.getAnswers(postId))
+        assertThatThrownBy(() -> answerService.getAnswers(postId, userId))
                 .isInstanceOf(DevpickException.class)
                 .satisfies(e -> assertThat(((DevpickException) e).getErrorCode())
                         .isEqualTo(ErrorCode.COMMUNITY_POST_NOT_FOUND));
     }
 
+    @Test
+    @DisplayName("getAnswers — 게시글 작성자가 타인의 미채택 답변 조회 시 canAdopt=true")
+    void getAnswers_postAuthor_othersAnswer_canAdoptTrue() {
+        UUID otherUserId = UUID.randomUUID();
+        User otherUser = User.builder().email("other@devpick.kr").nickname("other").job(Job.FRONTEND).level(Level.JUNIOR).build();
+        ReflectionTestUtils.setField(otherUser, "id", otherUserId);
+
+        Answer otherAnswer = Answer.builder().post(post).user(otherUser).content("Other Answer").build();
+        ReflectionTestUtils.setField(otherAnswer, "id", UUID.randomUUID());
+
+        given(postRepository.findById(postId)).willReturn(Optional.of(post));
+        given(answerRepository.findByPost_IdOrderByCreatedAtAsc(postId)).willReturn(List.of(otherAnswer));
+        given(commentRepository.findByAnswer_IdOrderByCreatedAtAsc(any())).willReturn(List.of());
+
+        AnswerListResponse response = answerService.getAnswers(postId, userId);
+
+        assertThat(response.answers().get(0).canAdopt()).isTrue();
+    }
+
+    @Test
+    @DisplayName("getAnswers — 게시글 작성자가 본인 답변 조회 시 canAdopt=false (본인 답변 채택 불가)")
+    void getAnswers_postAuthor_ownAnswer_canAdoptFalse() {
+        given(postRepository.findById(postId)).willReturn(Optional.of(post));
+        given(answerRepository.findByPost_IdOrderByCreatedAtAsc(postId)).willReturn(List.of(answer));
+        given(commentRepository.findByAnswer_IdOrderByCreatedAtAsc(answerId)).willReturn(List.of());
+
+        AnswerListResponse response = answerService.getAnswers(postId, userId);
+
+        assertThat(response.answers().get(0).canAdopt()).isFalse();
+    }
+
+    @Test
+    @DisplayName("getAnswers — 게시글 작성자가 아닌 유저는 canAdopt=false")
+    void getAnswers_notPostAuthor_canAdoptFalse() {
+        UUID otherUserId = UUID.randomUUID();
+        given(postRepository.findById(postId)).willReturn(Optional.of(post));
+        given(answerRepository.findByPost_IdOrderByCreatedAtAsc(postId)).willReturn(List.of(answer));
+        given(commentRepository.findByAnswer_IdOrderByCreatedAtAsc(answerId)).willReturn(List.of());
+
+        AnswerListResponse response = answerService.getAnswers(postId, otherUserId);
+
+        assertThat(response.answers().get(0).canAdopt()).isFalse();
+    }
+
+    @Test
+    @DisplayName("getAnswers — 이미 채택된 답변이 있으면 모든 답변에 canAdopt=false")
+    void getAnswers_anyAnswerAlreadyAdopted_canAdoptFalse() {
+        UUID otherUserId = UUID.randomUUID();
+        User otherUser = User.builder().email("other@devpick.kr").nickname("other").job(Job.FRONTEND).level(Level.JUNIOR).build();
+        ReflectionTestUtils.setField(otherUser, "id", otherUserId);
+
+        Answer adoptedAnswer = Answer.builder().post(post).user(otherUser).content("Adopted Answer").build();
+        ReflectionTestUtils.setField(adoptedAnswer, "id", UUID.randomUUID());
+        adoptedAnswer.adopt();
+
+        given(postRepository.findById(postId)).willReturn(Optional.of(post));
+        given(answerRepository.findByPost_IdOrderByCreatedAtAsc(postId)).willReturn(List.of(adoptedAnswer));
+        given(commentRepository.findByAnswer_IdOrderByCreatedAtAsc(any())).willReturn(List.of());
+
+        AnswerListResponse response = answerService.getAnswers(postId, userId);
+
+        assertThat(response.answers().get(0).canAdopt()).isFalse();
+    }
+
     @Test
     @DisplayName("createAnswer — 성공 시 답변 저장 후 반환")    void createAnswer_success_savesAndReturns() {
         AnswerCreateRequest request = new AnswerCreateRequest("Test Answer");
@@ -231,9 +296,15 @@ void deleteAnswer_unauthorized_throwsException() {
     @Test
     @DisplayName("adoptAnswer — 성공 시 isAdopted=true, isEdited는 변경되지 않는다")
     void adoptAnswer_success_adoptsAnswer() {
+        UUID otherUserId = UUID.randomUUID();
+        User otherUser = User.builder().email("other@devpick.kr").nickname("other").job(Job.BACKEND).level(Level.JUNIOR).build();
+        ReflectionTestUtils.setField(otherUser, "id", otherUserId);
+        Answer otherAnswer = Answer.builder().post(post).user(otherUser).content("Other Answer").build();
+        ReflectionTestUtils.setField(otherAnswer, "id", answerId);
+
         given(postRepository.findById(postId)).willReturn(Optional.of(post));
         given(answerRepository.findAdoptedByPostIdForUpdate(postId)).willReturn(List.of());
-        given(answerRepository.findById(answerId)).willReturn(Optional.of(answer));
+        given(answerRepository.findById(answerId)).willReturn(Optional.of(otherAnswer));
 
         AnswerResponse response = answerService.adoptAnswer(userId, postId, answerId);
 
@@ -279,4 +350,17 @@ void adoptAnswer_answerNotFound_throwsException() {
                 .satisfies(e -> assertThat(((DevpickException) e).getErrorCode())
                         .isEqualTo(ErrorCode.COMMUNITY_ANSWER_NOT_FOUND));
     }
+
+    @Test
+    @DisplayName("adoptAnswer — 본인 답변 채택 시 COMMUNITY_CANNOT_ADOPT_OWN_ANSWER 예외")
+    void adoptAnswer_ownAnswer_throwsException() {
+        given(postRepository.findById(postId)).willReturn(Optional.of(post));
+        given(answerRepository.findAdoptedByPostIdForUpdate(postId)).willReturn(List.of());
+        given(answerRepository.findById(answerId)).willReturn(Optional.of(answer)); // answer.user == post.user == userId
+
+        assertThatThrownBy(() -> answerService.adoptAnswer(userId, postId, answerId))
+                .isInstanceOf(DevpickException.class)
+                .satisfies(e -> assertThat(((DevpickException) e).getErrorCode())
+                        .isEqualTo(ErrorCode.COMMUNITY_CANNOT_ADOPT_OWN_ANSWER));
+    }
 }