Step1 qna refactoring

src/main/java/qna/domain/Answers.java

@@ -0,0 +1,30 @@
+package qna.domain;
+
+import qna.CannotDeleteException;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class Answers {
+    private final List<Answer> answers = new ArrayList<>();
+
+    public void add(Answer answer) {
+        answers.add(answer);
+    }
+
+    public List<Answer> getAnswers() {
+        return Collections.unmodifiableList(this.answers);
+    }
+
+    public boolean validateItHasOtherAnswer(User loginUser) throws CannotDeleteException {
+        for (Answer answer : this.answers) {
+
+            if (!answer.isOwner(loginUser)) {
+                throw new CannotDeleteException("다른 사람이 쓴 답변이 있어 삭제할 수 없습니다.");
+            }
+        }
+
+        return true;
+    }
+}

src/main/java/qna/domain/Question.java

@@ -1,6 +1,7 @@
 package qna.domain;
 
 import org.hibernate.annotations.Where;
+import qna.CannotDeleteException;
 
 import javax.persistence.*;
 import java.util.ArrayList;
@@ -21,7 +22,7 @@ public class Question extends AbstractEntity {
     @OneToMany(mappedBy = "question", cascade = CascadeType.ALL)
     @Where(clause = "deleted = false")
     @OrderBy("id ASC")
-    private List<Answer> answers = new ArrayList<>();
+    private Answers answers = new Answers();
 
     private boolean deleted = false;
 
@@ -84,12 +85,20 @@ public boolean isDeleted() {
         return deleted;
     }
 
-    public List<Answer> getAnswers() {
-        return answers;
+    public Answers getAnswers() {
+        return this.answers;
     }
 
     @Override
     public String toString() {
         return "Question [id=" + getId() + ", title=" + title + ", contents=" + contents + ", writer=" + writer + "]";
     }
+
+    public boolean validateItIsOtherUser(User loginUser) throws CannotDeleteException {
+        if (!this.isOwner(loginUser)) {
+            throw new CannotDeleteException("질문을 삭제할 권한이 없습니다.");
+        }
+
+        return true;
+    }
 }

src/main/java/qna/service/QnAService.java

@@ -35,21 +35,15 @@ public Question findQuestionById(Long id) {
     @Transactional
     public void deleteQuestion(User loginUser, long questionId) throws CannotDeleteException {
         Question question = findQuestionById(questionId);
-        if (!question.isOwner(loginUser)) {
-            throw new CannotDeleteException("질문을 삭제할 권한이 없습니다.");
-        }
+        question.validateItIsOtherUser(loginUser);
 
-        List<Answer> answers = question.getAnswers();
-        for (Answer answer : answers) {
-            if (!answer.isOwner(loginUser)) {
-                throw new CannotDeleteException("다른 사람이 쓴 답변이 있어 삭제할 수 없습니다.");
-            }
-        }
+        Answers answers = question.getAnswers();
+        answers.validateItHasOtherAnswer(loginUser);
 
         List<DeleteHistory> deleteHistories = new ArrayList<>();
         question.setDeleted(true);
         deleteHistories.add(new DeleteHistory(ContentType.QUESTION, questionId, question.getWriter(), LocalDateTime.now()));
-        for (Answer answer : answers) {
+        for (Answer answer : answers.getAnswers()) {
             answer.setDeleted(true);
             deleteHistories.add(new DeleteHistory(ContentType.ANSWER, answer.getId(), answer.getWriter(), LocalDateTime.now()));
         }

src/test/java/qna/domain/AnswersTest.java

@@ -0,0 +1,35 @@
+package qna.domain;
+
+import org.junit.jupiter.api.Test;
+import qna.CannotDeleteException;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+public class AnswersTest {
+    @Test
+    void validateItHasOtherAnswer_invalid() throws CannotDeleteException {
+        Answers answers = new Answers();
+
+        User otherUser = new User(11L, "applepickker", "abc112", "cho", "[email protected]");
+        Answer answer = new Answer(otherUser, new Question(), "contents");
+        answers.add(answer);
+
+        User loginUser = new User(12L, "dal96k", "wjsdnals96", "woomin", "[email protected]");
+
+        assertThatThrownBy(() ->
+            answers.validateItHasOtherAnswer(loginUser))
+                .isInstanceOf(CannotDeleteException.class);
+    }
+
+    @Test
+    void validateItHasOtherAnswer_valid() throws CannotDeleteException {
+        Answers answers = new Answers();
+
+        User loginUser = new User(11L, "dal96k", "wjsdnals96", "woomin", "[email protected]");
+        Answer answer = new Answer(loginUser, new Question(), "contents");
+        answers.add(answer);
+
+        assertThat(answers.validateItHasOtherAnswer(loginUser)).isEqualTo(true);
+    }
+}

src/test/java/qna/domain/QuestionTest.java

@@ -1,6 +1,35 @@
 package qna.domain;
 
+import org.junit.jupiter.api.Test;
+import qna.CannotDeleteException;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
 public class QuestionTest {
     public static final Question Q1 = new Question("title1", "contents1").writeBy(UserTest.JAVAJIGI);
     public static final Question Q2 = new Question("title2", "contents2").writeBy(UserTest.SANJIGI);
+
+    @Test
+    void validateItIsOtherUser_invalid() {
+        Question question = new Question(11L, "wonder", "this contents");
+        User otherUser = new User(11L, "applepickker", "abc112", "cho", "[email protected]");
+        question.writeBy(otherUser);
+
+        User loginUser = new User(12L, "dal96k", "wjsdnals96", "woomin", "[email protected]");
+
+        assertThatThrownBy(() ->
+                question.validateItIsOtherUser(loginUser))
+                    .isInstanceOf(CannotDeleteException.class);
+    }
+
+    @Test
+    void validateItIsOtherUser_valid() throws CannotDeleteException {
+        Question question = new Question(12, "wonder", "this contents");
+
+        User loginUser = new User(12L, "dal96k", "wjsdnals96", "woomin", "[email protected]");
+        question.writeBy(loginUser);
+
+        assertThat(question.validateItIsOtherUser(loginUser)).isEqualTo(true);
+    }
 }