Implement quiz attempt start service

src/main/java/com/example/questionbank/repository/ExamAttemptRepository.java

@@ -2,6 +2,7 @@ package com.example.questionbank.repository;
 
 import com.example.questionbank.domain.ExamAttempt;
 import java.util.List;
+import java.util.List;
 import java.util.Optional;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
@@ -14,6 +15,8 @@ import org.springframework.stereotype.Repository;
  */
 @Repository
 public interface ExamAttemptRepository extends JpaRepository<ExamAttempt, Long> {
+    List<ExamAttempt> findAllByUserLogin(String login);
+
     @Query("select examAttempt from ExamAttempt examAttempt where examAttempt.user.login = ?#{authentication.name}")
     List<ExamAttempt> findByUserIsCurrentUser();
 

src/main/java/com/example/questionbank/repository/QuestionRepository.java

@@ -2,6 +2,7 @@ package com.example.questionbank.repository;
 
 import com.example.questionbank.domain.Question;
 import java.util.List;
+import java.util.List;
 import java.util.Optional;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
@@ -14,6 +15,8 @@ import org.springframework.stereotype.Repository;
  */
 @Repository
 public interface QuestionRepository extends JpaRepository<Question, Long> {
+    List<Question> findAllBySubjectIdAndActiveTrue(Long subjectId);
+
     default Optional<Question> findOneWithEagerRelationships(Long id) {
         return this.findOneWithToOneRelationships(id);
     }

src/main/java/com/example/questionbank/service/quiz/ExamScoringService.java

@@ -0,0 +1,15 @@
+package com.example.questionbank.service.quiz;
+
+import com.example.questionbank.domain.enumeration.OptionKey;
+import org.springframework.stereotype.Service;
+
+@Service
+public class ExamScoringService {
+
+    public ScoringResult score(OptionKey correctOption, OptionKey selectedOption) {
+        boolean correct = selectedOption != null && selectedOption == correctOption;
+        return new ScoringResult(correct, correct ? 1 : 0);
+    }
+
+    public record ScoringResult(boolean correct, int awardedPoints) {}
+}

src/main/java/com/example/questionbank/service/quiz/QuizAttemptService.java

@@ -0,0 +1,70 @@
+package com.example.questionbank.service.quiz;
+
+import com.example.questionbank.domain.ExamAttempt;
+import com.example.questionbank.domain.Question;
+import com.example.questionbank.domain.Subject;
+import com.example.questionbank.domain.User;
+import com.example.questionbank.domain.enumeration.AttemptStatus;
+import com.example.questionbank.repository.ExamAttemptRepository;
+import com.example.questionbank.repository.QuestionRepository;
+import com.example.questionbank.repository.SubjectRepository;
+import com.example.questionbank.repository.UserRepository;
+import com.example.questionbank.web.rest.dto.ExamAttemptStartResult;
+import java.time.Instant;
+import java.util.List;
+import org.springframework.http.HttpStatus;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+import org.springframework.web.server.ResponseStatusException;
+
+@Service
+public class QuizAttemptService {
+
+    private final ExamAttemptRepository attemptRepository;
+    private final SubjectRepository subjectRepository;
+    private final QuestionRepository questionRepository;
+    private final UserRepository userRepository;
+
+    public QuizAttemptService(
+        ExamAttemptRepository attemptRepository,
+        SubjectRepository subjectRepository,
+        QuestionRepository questionRepository,
+        UserRepository userRepository
+    ) {
+        this.attemptRepository = attemptRepository;
+        this.subjectRepository = subjectRepository;
+        this.questionRepository = questionRepository;
+        this.userRepository = userRepository;
+    }
+
+    @Transactional
+    public ExamAttemptStartResult start(Long subjectId, String login) {
+        Subject subject = subjectRepository
+            .findById(subjectId)
+            .orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND, "과목을 찾을 수 없습니다."));
+
+        if (!Boolean.TRUE.equals(subject.getActive())) {
+            throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "비활성 과목은 응시할 수 없습니다.");
+        }
+
+        List<Question> activeQuestions = questionRepository.findAllBySubjectIdAndActiveTrue(subjectId);
+
+        if (activeQuestions.isEmpty()) {
+            throw new ResponseStatusException(HttpStatus.CONFLICT, "출제된 활성 문항이 없는 과목입니다.");
+        }
+
+        User user = userRepository
+            .findOneByLogin(login)
+            .orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND, "사용자를 찾을 수 없습니다."));
+
+        ExamAttempt attempt = new ExamAttempt();
+        attempt.setSubject(subject);
+        attempt.setUser(user);
+        attempt.setStartedAt(Instant.now());
+        attempt.setStatus(AttemptStatus.IN_PROGRESS);
+        attempt.setScore(0);
+
+        ExamAttempt saved = attemptRepository.save(attempt);
+        return new ExamAttemptStartResult(saved.getId(), saved.getStartedAt());
+    }
+}

src/main/java/com/example/questionbank/web/rest/dto/AnswerResult.java

@@ -0,0 +1,13 @@
+package com.example.questionbank.web.rest.dto;
+
+import com.example.questionbank.domain.enumeration.OptionKey;
+
+public record AnswerResult(
+    Long questionId,
+    String questionText,
+    OptionKey selectedOption,
+    String selectedContent,
+    boolean correct,
+    int awardedPoints,
+    String explanation
+) {}

src/main/java/com/example/questionbank/web/rest/dto/ChoiceView.java

@@ -0,0 +1,5 @@
+package com.example.questionbank.web.rest.dto;
+
+import com.example.questionbank.domain.enumeration.OptionKey;
+
+public record ChoiceView(OptionKey optionKey, String content, Integer displayOrder) {}

src/main/java/com/example/questionbank/web/rest/dto/ExamAttemptStartResult.java

@@ -0,0 +1,5 @@
+package com.example.questionbank.web.rest.dto;
+
+import java.time.Instant;
+
+public record ExamAttemptStartResult(Long attemptId, Instant startedAt) {}

src/main/java/com/example/questionbank/web/rest/dto/ExamAttemptSummary.java

@@ -0,0 +1,14 @@
+package com.example.questionbank.web.rest.dto;
+
+import com.example.questionbank.domain.enumeration.AttemptStatus;
+import java.time.Instant;
+
+public record ExamAttemptSummary(
+    Long attemptId,
+    Long subjectId,
+    String subjectName,
+    Instant startedAt,
+    Instant submittedAt,
+    AttemptStatus status,
+    Integer score
+) {}

src/main/java/com/example/questionbank/web/rest/dto/ExamQuestionView.java

@@ -0,0 +1,5 @@
+package com.example.questionbank.web.rest.dto;
+
+import java.util.List;
+
+public record ExamQuestionView(Long questionId, String prompt, List<ChoiceView> choices) {}

src/main/java/com/example/questionbank/web/rest/dto/ExamResult.java

@@ -0,0 +1,6 @@
+package com.example.questionbank.web.rest.dto;
+
+import java.time.Instant;
+import java.util.List;
+
+public record ExamResult(Long attemptId, int totalScore, Instant submittedAt, List<AnswerResult> answers) {}

src/main/java/com/example/questionbank/web/rest/dto/StartExamRequest.java

@@ -0,0 +1,5 @@
+package com.example.questionbank.web.rest.dto;
+
+import jakarta.validation.constraints.NotNull;
+
+public record StartExamRequest(@NotNull Long subjectId) {}

src/main/java/com/example/questionbank/web/rest/dto/SubmitAnswerRequest.java

@@ -0,0 +1,6 @@
+package com.example.questionbank.web.rest.dto;
+
+import com.example.questionbank.domain.enumeration.OptionKey;
+import jakarta.validation.constraints.NotNull;
+
+public record SubmitAnswerRequest(@NotNull Long questionId, OptionKey selectedOption) {}

src/main/java/com/example/questionbank/web/rest/dto/SubmitExamRequest.java

@@ -0,0 +1,7 @@
+package com.example.questionbank.web.rest.dto;
+
+import jakarta.validation.Valid;
+import jakarta.validation.constraints.NotEmpty;
+import java.util.List;
+
+public record SubmitExamRequest(@NotEmpty List<@Valid SubmitAnswerRequest> answers) {}

src/test/java/com/example/questionbank/service/quiz/ExamScoringServiceTest.java

@@ -0,0 +1,37 @@
+package com.example.questionbank.service.quiz;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import com.example.questionbank.domain.enumeration.OptionKey;
+import org.junit.jupiter.api.Test;
+
+class ExamScoringServiceTest {
+
+    private final ExamScoringService service = new ExamScoringService();
+
+    @Test
+    void correctAnswerGetsOnePoint() {
+        var result = service.score(OptionKey.A, OptionKey.A);
+
+        assertTrue(result.correct());
+        assertEquals(1, result.awardedPoints());
+    }
+
+    @Test
+    void wrongAnswerGetsZeroPoints() {
+        var result = service.score(OptionKey.A, OptionKey.D);
+
+        assertFalse(result.correct());
+        assertEquals(0, result.awardedPoints());
+    }
+
+    @Test
+    void unansweredQuestionGetsZeroPoints() {
+        var result = service.score(OptionKey.A, null);
+
+        assertFalse(result.correct());
+        assertEquals(0, result.awardedPoints());
+    }
+}