Step1

src/main/java/nextstep/qna/domain/Answer.java

@@ -1,11 +1,12 @@
 package nextstep.qna.domain;
 
+import java.time.LocalDateTime;
+
+import nextstep.qna.CannotDeleteException;
 import nextstep.qna.NotFoundException;
 import nextstep.qna.UnAuthorizedException;
 import nextstep.users.domain.NsUser;
 
-import java.time.LocalDateTime;
-
 public class Answer {
     private Long id;
 
@@ -30,11 +31,11 @@ public Answer(NsUser writer, Question question, String contents) {
 
     public Answer(Long id, NsUser writer, Question question, String contents) {
         this.id = id;
-        if(writer == null) {
+        if (writer == null) {
             throw new UnAuthorizedException();
         }
 
-        if(question == null) {
+        if (question == null) {
             throw new NotFoundException();
         }
 
@@ -43,15 +44,6 @@ public Answer(Long id, NsUser writer, Question question, String contents) {
         this.contents = contents;
     }
 
-    public Long getId() {
-        return id;
-    }
-
-    public Answer setDeleted(boolean deleted) {
-        this.deleted = deleted;
-        return this;
-    }
-
     public boolean isDeleted() {
         return deleted;
     }
@@ -60,20 +52,24 @@ public boolean isOwner(NsUser writer) {
         return this.writer.equals(writer);
     }
 
-    public NsUser getWriter() {
-        return writer;
-    }
-
-    public String getContents() {
-        return contents;
-    }
-
     public void toQuestion(Question question) {
         this.question = question;
     }
 
     @Override
     public String toString() {
-        return "Answer [id=" + getId() + ", writer=" + writer + ", contents=" + contents + "]";
+        return "Answer [id=" + id + ", writer=" + writer + ", contents=" + contents + "]";
+    }
+
+    public DeleteHistory delete(NsUser loginUser, LocalDateTime createdDate) throws CannotDeleteException {
+        validate(loginUser);
+        this.deleted = true;
+        return new DeleteHistory(ContentType.ANSWER, this.id, this.writer, createdDate);
+    }
+
+    private void validate(NsUser loginUser) throws CannotDeleteException {
+        if (!isOwner(loginUser)) {
+            throw new CannotDeleteException("다른 사람이 쓴 답변이 있어 삭제할 수 없습니다.");
+        }
     }
 }

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

@@ -0,0 +1,24 @@
+package nextstep.qna.domain;
+
+import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.List;
+
+import nextstep.qna.CannotDeleteException;
+import nextstep.users.domain.NsUser;
+
+public class Answers {
+    private final List<Answer> answers = new ArrayList<>();
+
+    public void add(Answer answer) {
+        answers.add(answer);
+    }
+
+    public List<DeleteHistory> delete(NsUser loginUser, LocalDateTime createdDate) throws CannotDeleteException {
+        final List<DeleteHistory> deleteHistories = new ArrayList<>();
+        for (Answer answer : this.answers) {
+            deleteHistories.add(answer.delete(loginUser, createdDate));
+        }
+        return deleteHistories;
+    }
+}

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

@@ -1,11 +1,12 @@
 package nextstep.qna.domain;
 
-import nextstep.users.domain.NsUser;
-
 import java.time.LocalDateTime;
 import java.util.ArrayList;
 import java.util.List;
 
+import nextstep.qna.CannotDeleteException;
+import nextstep.users.domain.NsUser;
+
 public class Question {
     private Long id;
 
@@ -15,7 +16,7 @@ public class Question {
 
     private NsUser writer;
 
-    private List<Answer> answers = new ArrayList<>();
+    private Answers answers = new Answers();
 
     private boolean deleted = false;
 
@@ -37,42 +38,16 @@ public Question(Long id, NsUser writer, String title, String contents) {
         this.contents = contents;
     }
 
-    public Long getId() {
-        return id;
-    }
-
-    public String getTitle() {
-        return title;
-    }
-
-    public Question setTitle(String title) {
-        this.title = title;
-        return this;
-    }
-
-    public String getContents() {
-        return contents;
-    }
-
-    public Question setContents(String contents) {
-        this.contents = contents;
-        return this;
-    }
-
-    public NsUser getWriter() {
-        return writer;
-    }
-
     public void addAnswer(Answer answer) {
         answer.toQuestion(this);
         answers.add(answer);
     }
 
-    public boolean isOwner(NsUser loginUser) {
+    private boolean isOwner(NsUser loginUser) {
         return writer.equals(loginUser);
     }
 
-    public Question setDeleted(boolean deleted) {
+    private Question setDeleted(boolean deleted) {
         this.deleted = deleted;
         return this;
     }
@@ -81,12 +56,26 @@ public boolean isDeleted() {
         return deleted;
     }
 
-    public List<Answer> getAnswers() {
-        return answers;
+    public List<DeleteHistory> delete(NsUser loginUser, LocalDateTime createdDate) throws CannotDeleteException {
+        validate(loginUser);
+
+        setDeleted(true);
+
+        List<DeleteHistory> deleteHistories = new ArrayList<>();
+        deleteHistories.add(new DeleteHistory(ContentType.QUESTION, this.id, this.writer, createdDate));
+        deleteHistories.addAll(answers.delete(loginUser, createdDate));
+
+        return deleteHistories;
+    }
+
+    private void validate(NsUser loginUser) throws CannotDeleteException {
+        if (!isOwner(loginUser)) {
+            throw new CannotDeleteException("질문을 삭제할 권한이 없습니다.");
+        }
     }
 
     @Override
     public String toString() {
-        return "Question [id=" + getId() + ", title=" + title + ", contents=" + contents + ", writer=" + writer + "]";
+        return "Question [id=" + id + ", title=" + title + ", contents=" + contents + ", writer=" + writer + "]";
     }
 }

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

@@ -1,16 +1,18 @@
 package nextstep.qna.service;
 
-import nextstep.qna.CannotDeleteException;
-import nextstep.qna.NotFoundException;
-import nextstep.qna.domain.*;
-import nextstep.users.domain.NsUser;
+import java.time.LocalDateTime;
+
+import javax.annotation.Resource;
+
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
-import javax.annotation.Resource;
-import java.time.LocalDateTime;
-import java.util.ArrayList;
-import java.util.List;
+import nextstep.qna.CannotDeleteException;
+import nextstep.qna.NotFoundException;
+import nextstep.qna.domain.AnswerRepository;
+import nextstep.qna.domain.Question;
+import nextstep.qna.domain.QuestionRepository;
+import nextstep.users.domain.NsUser;
 
 @Service("qnaService")
 public class QnAService {
@@ -26,24 +28,6 @@ public class QnAService {
     @Transactional
     public void deleteQuestion(NsUser loginUser, long questionId) throws CannotDeleteException {
         Question question = questionRepository.findById(questionId).orElseThrow(NotFoundException::new);
-        if (!question.isOwner(loginUser)) {
-            throw new CannotDeleteException("질문을 삭제할 권한이 없습니다.");
-        }
-
-        List<Answer> answers = question.getAnswers();
-        for (Answer answer : answers) {
-            if (!answer.isOwner(loginUser)) {
-                throw new CannotDeleteException("다른 사람이 쓴 답변이 있어 삭제할 수 없습니다.");
-            }
-        }
-
-        List<DeleteHistory> deleteHistories = new ArrayList<>();
-        question.setDeleted(true);
-        deleteHistories.add(new DeleteHistory(ContentType.QUESTION, questionId, question.getWriter(), LocalDateTime.now()));
-        for (Answer answer : answers) {
-            answer.setDeleted(true);
-            deleteHistories.add(new DeleteHistory(ContentType.ANSWER, answer.getId(), answer.getWriter(), LocalDateTime.now()));
-        }
-        deleteHistoryService.saveAll(deleteHistories);
+        deleteHistoryService.saveAll(question.delete(loginUser, LocalDateTime.now()));
     }
 }

src/test/java/nextstep/qna/domain/AnswerTest.java

@@ -1,8 +1,27 @@
 package nextstep.qna.domain;
 
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+
+import java.time.LocalDateTime;
+
+import org.junit.jupiter.api.Test;
+
+import nextstep.qna.CannotDeleteException;
 import nextstep.users.domain.NsUserTest;
 
 public class AnswerTest {
     public static final Answer A1 = new Answer(NsUserTest.JAVAJIGI, QuestionTest.Q1, "Answers Contents1");
     public static final Answer A2 = new Answer(NsUserTest.SANJIGI, QuestionTest.Q1, "Answers Contents2");
+
+    @Test
+    void delete() throws CannotDeleteException {
+        final LocalDateTime createdDate = LocalDateTime.now();
+        assertThat(A1.delete(NsUserTest.JAVAJIGI, createdDate)).isEqualTo(new DeleteHistory(ContentType.ANSWER, null, NsUserTest.JAVAJIGI, createdDate));
+    }
+
+    @Test
+    void 다른_사람이_쓴_답변이_있어_삭제할_수_없습니다() {
+        assertThatExceptionOfType(CannotDeleteException.class).isThrownBy(() -> A1.delete(NsUserTest.SANJIGI, LocalDateTime.now()));
+    }
 }

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

@@ -1,8 +1,31 @@
 package nextstep.qna.domain;
 
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+
+import java.time.LocalDateTime;
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import nextstep.qna.CannotDeleteException;
 import nextstep.users.domain.NsUserTest;
 
+@ExtendWith(MockitoExtension.class)
 public class QuestionTest {
     public static final Question Q1 = new Question(NsUserTest.JAVAJIGI, "title1", "contents1");
     public static final Question Q2 = new Question(NsUserTest.SANJIGI, "title2", "contents2");
+
+    @Test
+    void delete() throws CannotDeleteException {
+        final LocalDateTime createdDate = LocalDateTime.now();
+        assertThat(Q1.delete(NsUserTest.JAVAJIGI, createdDate)).isEqualTo(List.of(new DeleteHistory(ContentType.QUESTION, 0L, NsUserTest.JAVAJIGI, createdDate)));
+    }
+
+    @Test
+    void 다른_사람이_쓴_질문이_있어_삭제할_수_없습니다() {
+        assertThatExceptionOfType(CannotDeleteException.class).isThrownBy(() -> Q1.delete(NsUserTest.SANJIGI, LocalDateTime.now()));
+    }
 }