Refactor exception handling in GlobalExceptionHandler and improve error

src/main/java/tools/vitruv/methodologist/setup/config/GlobalExceptionHandler.java

@@ -1,13 +1,14 @@
 package tools.vitruv.methodologist.setup.config;
 
+import com.fasterxml.jackson.databind.ObjectMapper;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import java.io.IOException;
 import java.nio.file.NoSuchFileException;
-import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.http.HttpStatus;
-import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.RestControllerAdvice;
-import org.springframework.web.context.request.WebRequest;
 import tools.vitruv.methodologist.setup.exception.ErrorResponseDTO;
 import tools.vitruv.methodologist.setup.exception.GenmodelException;
 import tools.vitruv.methodologist.setup.exception.MethodologistSetupException;
@@ -19,101 +20,95 @@
  */
 @Slf4j
 @RestControllerAdvice(basePackages = "tools.vitruv.methodologist.setup")
-@RequiredArgsConstructor
 public class GlobalExceptionHandler {
+  private final ObjectMapper objectMapper = new ObjectMapper();
 
   /**
    * Handles MethodologistSetupException.
    *
    * @param ex the exception
    * @param request the web request
-   * @return error response
    */
   @ExceptionHandler(MethodologistSetupException.class)
-  public ResponseEntity<ErrorResponseDTO> handleMethodologistSetupException(
-      MethodologistSetupException ex, WebRequest request) {
+  public void handleMethodologistSetupException(
+      MethodologistSetupException ex, HttpServletRequest request, HttpServletResponse response)
+      throws IOException {
     log.error("MethodologistSetupException occurred: {}", ex.getMessage(), ex);
 
-    ErrorResponseDTO errorResponse =
-        ErrorResponseDTO.builder()
-            .errorCode(ex.getErrorCode())
-            .message(ex.getMessage())
-            .status(HttpStatus.BAD_REQUEST.value())
-            .timestamp(System.currentTimeMillis())
-            .path(request.getDescription(false).replace("uri=", ""))
-            .build();
-
-    return new ResponseEntity<>(errorResponse, HttpStatus.BAD_REQUEST);
+    writeErrorResponse(
+        response, request, HttpStatus.BAD_REQUEST, ex.getErrorCode(), ex.getMessage());
   }
 
   /**
    * Handles GenmodelException.
    *
    * @param ex the exception
    * @param request the web request
-   * @return error response
    */
   @ExceptionHandler(GenmodelException.class)
-  public ResponseEntity<ErrorResponseDTO> handleGenmodelException(
-      GenmodelException ex, WebRequest request) {
+  public void handleGenmodelException(
+      GenmodelException ex, HttpServletRequest request, HttpServletResponse response)
+      throws IOException {
     log.error("GenmodelException occurred: {}", ex.getMessage(), ex);
 
-    ErrorResponseDTO errorResponse =
-        ErrorResponseDTO.builder()
-            .errorCode(ex.getErrorCode())
-            .message(ex.getMessage())
-            .status(HttpStatus.UNPROCESSABLE_ENTITY.value())
-            .timestamp(System.currentTimeMillis())
-            .path(request.getDescription(false).replace("uri=", ""))
-            .build();
-
-    return new ResponseEntity<>(errorResponse, HttpStatus.UNPROCESSABLE_ENTITY);
+    writeErrorResponse(
+        response, request, HttpStatus.UNPROCESSABLE_ENTITY, ex.getErrorCode(), ex.getMessage());
   }
 
   /**
    * Handles NoSuchFileException raised when an expected build artifact is missing.
    *
    * @param ex the exception
    * @param request the web request
-   * @return error response with bad request status
    */
   @ExceptionHandler(NoSuchFileException.class)
-  public ResponseEntity<ErrorResponseDTO> handleNoSuchFileException(
-      NoSuchFileException ex, WebRequest request) {
+  public void handleNoSuchFileException(
+      NoSuchFileException ex, HttpServletRequest request, HttpServletResponse response)
+      throws IOException {
     log.error("NoSuchFileException occurred: {}", ex.getMessage(), ex);
 
-    ErrorResponseDTO errorResponse =
-        ErrorResponseDTO.builder()
-            .errorCode("VSUM_ARTIFACT_NOT_FOUND")
-            .message(ex.getMessage())
-            .status(HttpStatus.BAD_REQUEST.value())
-            .timestamp(System.currentTimeMillis())
-            .path(request.getDescription(false).replace("uri=", ""))
-            .build();
-
-    return new ResponseEntity<>(errorResponse, HttpStatus.BAD_REQUEST);
+    writeErrorResponse(
+        response, request, HttpStatus.BAD_REQUEST, "VSUM_ARTIFACT_NOT_FOUND", ex.getMessage());
   }
 
   /**
    * Handles all other exceptions.
    *
    * @param ex the exception
    * @param request the web request
-   * @return error response
    */
   @ExceptionHandler(Exception.class)
-  public ResponseEntity<ErrorResponseDTO> handleGlobalException(Exception ex, WebRequest request) {
+  public void handleGlobalException(
+      Exception ex, HttpServletRequest request, HttpServletResponse response) throws IOException {
     log.error("Unexpected exception occurred: {}", ex.getMessage(), ex);
 
+    writeErrorResponse(
+        response,
+        request,
+        HttpStatus.INTERNAL_SERVER_ERROR,
+        "INTERNAL_ERROR",
+        ErrorMessages.UNEXPECTED_ERROR);
+  }
+
+  private void writeErrorResponse(
+      HttpServletResponse response,
+      HttpServletRequest request,
+      HttpStatus status,
+      String errorCode,
+      String message)
+      throws IOException {
     ErrorResponseDTO errorResponse =
         ErrorResponseDTO.builder()
-            .errorCode("INTERNAL_ERROR")
-            .message(ErrorMessages.UNEXPECTED_ERROR)
-            .status(HttpStatus.INTERNAL_SERVER_ERROR.value())
+            .errorCode(errorCode)
+            .message(message)
+            .status(status.value())
             .timestamp(System.currentTimeMillis())
-            .path(request.getDescription(false).replace("uri=", ""))
+            .path(request.getRequestURI())
             .build();
 
-    return new ResponseEntity<>(errorResponse, HttpStatus.INTERNAL_SERVER_ERROR);
+    response.setStatus(status.value());
+    response.setCharacterEncoding("UTF-8");
+    response.setContentType("application/json");
+    response.getWriter().write(objectMapper.writeValueAsString(errorResponse));
   }
 }

src/main/java/tools/vitruv/methodologist/setup/vsum/service/VsumProjectBuildService.java

@@ -100,12 +100,14 @@ private byte[] buildArtifact(
       Map<String, String> metamodelNamespaceMap = extractMetamodelNamespaceMap(modelPairs);
       return generator.generate(modelPairs, copiedReactionFiles, metamodelNamespaceMap);
     } catch (IOException | MissingModelException e) {
+      String reason = e.getMessage() != null ? e.getMessage() : e.toString();
       throw new MethodologistSetupException(
-          VSUM_BUILD_ERROR_CODE, "Failed to build VSUM project archive", e);
+          VSUM_BUILD_ERROR_CODE, "Failed to build VSUM project archive: " + reason, e);
     } catch (InterruptedException e) {
       Thread.currentThread().interrupt();
+      String reason = e.getMessage() != null ? e.getMessage() : e.toString();
       throw new MethodologistSetupException(
-          VSUM_BUILD_ERROR_CODE, "VSUM project build was interrupted", e);
+          VSUM_BUILD_ERROR_CODE, "VSUM project build was interrupted: " + reason, e);
     } finally {
       deleteRecursively(uploadWorkspace);
     }
@@ -134,7 +136,10 @@ private void validateInputs(
     if (metamodelFiles.size() != genmodelFiles.size()) {
       throw new MethodologistSetupException(
           VSUM_INPUT_ERROR_CODE,
-          "Metamodel and genmodel file counts must be identical to build file pairs");
+          String.format(
+              "Please upload the same number of metamodel and genmodel files "
+                  + "(received %d metamodel file(s) and %d genmodel file(s)).",
+              metamodelFiles.size(), genmodelFiles.size()));
     }
 
     for (MultipartFile file : metamodelFiles) {

src/test/java/tools/vitruv/methodologist/setup/vsum/controller/VsumControllerErrorHandlingTest.java

@@ -0,0 +1,64 @@
+package tools.vitruv.methodologist.setup.vsum.controller;
+
+import static org.mockito.ArgumentMatchers.anyList;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.multipart;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.http.MediaType;
+import org.springframework.mock.web.MockMultipartFile;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.setup.MockMvcBuilders;
+import tools.vitruv.methodologist.setup.config.GlobalExceptionHandler;
+import tools.vitruv.methodologist.setup.exception.MethodologistSetupException;
+import tools.vitruv.methodologist.setup.vsum.service.VsumProjectBuildService;
+
+@ExtendWith(MockitoExtension.class)
+class VsumControllerErrorHandlingTest {
+
+  @Test
+  void buildProject_shouldReturnJsonErrorForZipAcceptHeader() throws Exception {
+    VsumProjectBuildService buildService = mock(VsumProjectBuildService.class);
+    VsumController controller = new VsumController(buildService);
+    MockMvc mockMvc =
+        MockMvcBuilders.standaloneSetup(controller)
+            .setControllerAdvice(new GlobalExceptionHandler())
+            .build();
+
+    when(buildService.buildProjectArchive(anyList(), anyList(), anyList()))
+        .thenThrow(
+            new MethodologistSetupException(
+                "VSUM_INPUT_ERROR",
+                "Please upload the same number of metamodel and genmodel files"));
+
+    MockMultipartFile metamodelFile =
+        new MockMultipartFile(
+            "metamodelFiles", "a.ecore", "application/xml", "<ecore/>".getBytes());
+    MockMultipartFile genmodelFile =
+        new MockMultipartFile(
+            "genmodelFiles", "a.genmodel", "application/xml", "<genmodel/>".getBytes());
+    MockMultipartFile reactionFile =
+        new MockMultipartFile(
+            "reactionFiles", "a.reactions", "text/plain", "import \"x\"".getBytes());
+
+    mockMvc
+        .perform(
+            multipart("/api/vsum/build")
+                .file(metamodelFile)
+                .file(genmodelFile)
+                .file(reactionFile)
+                .accept(MediaType.parseMediaType("application/zip")))
+        .andExpect(status().isBadRequest())
+        .andExpect(content().contentTypeCompatibleWith(MediaType.APPLICATION_JSON))
+        .andExpect(jsonPath("$.errorCode").value("VSUM_INPUT_ERROR"))
+        .andExpect(
+            jsonPath("$.message")
+                .value("Please upload the same number of metamodel and genmodel files"));
+  }
+}

src/test/java/tools/vitruv/methodologist/setup/vsum/service/VsumProjectBuildServiceTest.java

@@ -55,7 +55,8 @@ void buildProjectArchive_shouldThrowWhenCountsDoNotMatch() {
                     List.of(mockMultipart("a.genmodel")),
                     List.of()))
         .isInstanceOf(MethodologistSetupException.class)
-        .hasMessageContaining("counts must be identical");
+        .hasMessageContaining("Please upload the same number of metamodel and genmodel files")
+        .hasMessageContaining("received 2 metamodel file(s) and 1 genmodel file(s)");
   }
 
   @Test
@@ -202,7 +203,8 @@ void buildProjectJar_shouldThrowWhenCountsDoNotMatch() {
                     List.of(mockMultipart("a.genmodel")),
                     List.of()))
         .isInstanceOf(MethodologistSetupException.class)
-        .hasMessageContaining("counts must be identical");
+        .hasMessageContaining("Please upload the same number of metamodel and genmodel files")
+        .hasMessageContaining("received 2 metamodel file(s) and 1 genmodel file(s)");
   }
 
   @Test