[BE] refactor: 서비스 리팩터링

backend/src/main/java/reviewme/review/service/module/TextAnswerValidator.java

@@ -1,24 +1,29 @@
 package reviewme.review.service.module;
 
+import lombok.RequiredArgsConstructor;
 import org.springframework.stereotype.Component;
+import reviewme.question.repository.QuestionRepository;
 import reviewme.review.domain.TextAnswer;
 import reviewme.review.domain.exception.InvalidTextAnswerLengthException;
-import reviewme.review.service.exception.QuestionNotAnsweredException;
+import reviewme.review.service.exception.SubmittedQuestionNotFoundException;
 
 @Component
+@RequiredArgsConstructor
 public class TextAnswerValidator {
 
     private static final int MIN_LENGTH = 20;
     private static final int MAX_LENGTH = 1_000;
 
+    private final QuestionRepository questionRepository;
+
     public void validate(TextAnswer textAnswer) {
-        validateAnswerExist(textAnswer);
+        validateExistQuestion(textAnswer);
         validateLength(textAnswer);
     }
 
-    private static void validateAnswerExist(TextAnswer textAnswer) {
-        if (textAnswer.getContent() == null) {
-            throw new QuestionNotAnsweredException(textAnswer.getId());
+    private void validateExistQuestion(TextAnswer textAnswer) {
+        if (!questionRepository.existsById(textAnswer.getQuestionId())) {
+            throw new SubmittedQuestionNotFoundException(textAnswer.getQuestionId());
         }
     }