Maintenance: ControllerAdvice - Add validation exception handlers and tests (#114)

Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>
Co-authored-by: Claude <[email protected]>

Author: 3 people

src/main/java/spring/memewikibe/api/controller/ControllerAdvice.java

@@ -4,13 +4,19 @@
 import org.slf4j.LoggerFactory;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
+import org.springframework.http.converter.HttpMessageNotReadableException;
+import org.springframework.validation.FieldError;
+import org.springframework.web.bind.MethodArgumentNotValidException;
 import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.RestControllerAdvice;
 import org.springframework.web.servlet.resource.NoResourceFoundException;
 import spring.memewikibe.support.error.ErrorType;
 import spring.memewikibe.support.error.MemeWikiApplicationException;
 import spring.memewikibe.support.response.ApiResponse;
 
+import java.util.HashMap;
+import java.util.Map;
+
 @RestControllerAdvice
 public class ControllerAdvice {
 
@@ -26,6 +32,31 @@ public ResponseEntity<ApiResponse<?>> handleCustomException(MemeWikiApplicationE
         return new ResponseEntity<>(ApiResponse.error(e.getErrorType(), e.getData()), e.getErrorType().getStatus());
     }
 
+    @ExceptionHandler(MethodArgumentNotValidException.class)
+    public ResponseEntity<ApiResponse<?>> handleValidationException(MethodArgumentNotValidException e) {
+        Map<String, String> errors = new HashMap<>();
+        e.getBindingResult().getAllErrors().forEach(error -> {
+            String fieldName = ((FieldError) error).getField();
+            String errorMessage = error.getDefaultMessage();
+            errors.put(fieldName, errorMessage);
+        });
+
+        log.warn("Validation failed: {}", errors);
+        return new ResponseEntity<>(
+            ApiResponse.error(ErrorType.EXTERNAL_SERVICE_BAD_REQUEST, errors),
+            HttpStatus.BAD_REQUEST
+        );
+    }
+
+    @ExceptionHandler(HttpMessageNotReadableException.class)
+    public ResponseEntity<ApiResponse<?>> handleHttpMessageNotReadable(HttpMessageNotReadableException e) {
+        log.warn("Malformed JSON request: {}", e.getMessage());
+        return new ResponseEntity<>(
+            ApiResponse.error(ErrorType.EXTERNAL_SERVICE_BAD_REQUEST, "올바르지 않은 요청 형식입니다."),
+            HttpStatus.BAD_REQUEST
+        );
+    }
+
     @ExceptionHandler(NoResourceFoundException.class)
     public ResponseEntity<Void> handleNoResourceFound(NoResourceFoundException e) {
         if (e.getMessage().contains("favicon.ico")) {

src/test/java/spring/memewikibe/api/controller/ControllerAdviceTest.java

@@ -0,0 +1,111 @@
+package spring.memewikibe.api.controller;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import jakarta.validation.Valid;
+import jakarta.validation.constraints.NotBlank;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.http.MediaType;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.setup.MockMvcBuilders;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RestController;
+import spring.memewikibe.support.error.ErrorType;
+import spring.memewikibe.support.error.MemeWikiApplicationException;
+import spring.memewikibe.support.response.ApiResponse;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+class ControllerAdviceTest {
+
+    private MockMvc mockMvc;
+    private ObjectMapper objectMapper;
+
+    @BeforeEach
+    void setUp() {
+        objectMapper = new ObjectMapper();
+        mockMvc = MockMvcBuilders.standaloneSetup(new TestController())
+            .setControllerAdvice(new ControllerAdvice())
+            .build();
+    }
+
+    @Test
+    @DisplayName("Validation 실패 시 필드별 에러 메시지를 반환한다")
+    void handleValidationException() throws Exception {
+        // given
+        TestRequest invalidRequest = new TestRequest("");
+
+        // when & then
+        mockMvc.perform(post("/test/validate")
+                .contentType(MediaType.APPLICATION_JSON)
+                .content(objectMapper.writeValueAsString(invalidRequest)))
+            .andExpect(status().isBadRequest())
+            .andExpect(jsonPath("$.resultType").value("ERROR"))
+            .andExpect(jsonPath("$.error.code").value("E400"))
+            .andExpect(jsonPath("$.error.data.name").exists());
+    }
+
+    @Test
+    @DisplayName("잘못된 JSON 형식 요청 시 적절한 에러 메시지를 반환한다")
+    void handleHttpMessageNotReadable() throws Exception {
+        // given
+        String malformedJson = "{invalid json}";
+
+        // when & then
+        mockMvc.perform(post("/test/validate")
+                .contentType(MediaType.APPLICATION_JSON)
+                .content(malformedJson))
+            .andExpect(status().isBadRequest())
+            .andExpect(jsonPath("$.resultType").value("ERROR"))
+            .andExpect(jsonPath("$.error.code").value("E400"));
+    }
+
+    @Test
+    @DisplayName("MemeWikiApplicationException 발생 시 적절한 에러 응답을 반환한다")
+    void handleCustomException() throws Exception {
+        // when & then
+        mockMvc.perform(post("/test/custom-error")
+                .contentType(MediaType.APPLICATION_JSON))
+            .andExpect(status().isNotFound())
+            .andExpect(jsonPath("$.resultType").value("ERROR"))
+            .andExpect(jsonPath("$.error.code").value("E404"))
+            .andExpect(jsonPath("$.error.message").value("존재하지 않는 밈입니다."));
+    }
+
+    @Test
+    @DisplayName("예상치 못한 예외 발생 시 기본 에러 응답을 반환한다")
+    void handleUnexpectedException() throws Exception {
+        // when & then
+        mockMvc.perform(post("/test/unexpected-error")
+                .contentType(MediaType.APPLICATION_JSON))
+            .andExpect(status().isInternalServerError())
+            .andExpect(jsonPath("$.resultType").value("ERROR"))
+            .andExpect(jsonPath("$.error.code").value("E500"));
+    }
+
+    // Test controller for exception handling tests
+    @RestController
+    static class TestController {
+
+        @PostMapping("/test/validate")
+        public ApiResponse<String> validate(@Valid @RequestBody TestRequest request) {
+            return ApiResponse.success("OK");
+        }
+
+        @PostMapping("/test/custom-error")
+        public ApiResponse<String> customError() {
+            throw new MemeWikiApplicationException(ErrorType.MEME_NOT_FOUND);
+        }
+
+        @PostMapping("/test/unexpected-error")
+        public ApiResponse<String> unexpectedError() {
+            throw new RuntimeException("Unexpected error occurred");
+        }
+    }
+
+    record TestRequest(@NotBlank(message = "이름은 필수입니다.") String name) {}
+}