Merge pull request #246 from maeil-mail/236

구독 기삭제 여부 판단 로직을 추가한다.

maeil-mail/src/main/java/maeilmail/subscribe/command/domain/Subscribe.java

@@ -63,8 +63,11 @@ private long determineSequenceByCategory(QuestionCategory category) {
         return 0L;
     }
 
-    // TODO: 기삭제 여부 판단
     public void unsubscribe() {
+        if (deletedAt != null) {
+            throw new IllegalStateException("이미 구독이 취소되었습니다.");
+        }
+
         this.deletedAt = LocalDateTime.now();
     }
 

maeil-mail/src/test/java/maeilmail/subscribe/command/domain/SubscribeTest.java

@@ -0,0 +1,36 @@
+package maeilmail.subscribe.command.domain;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import maeilmail.question.QuestionCategory;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+class SubscribeTest {
+
+    @Test
+    @DisplayName("구독을 취소할 수 있다.")
+    void unsubscribe() {
+        Subscribe subscribe = createSubscribe();
+
+        subscribe.unsubscribe();
+
+        assertThat(subscribe.getDeletedAt()).isNotNull();
+    }
+
+    @Test
+    @DisplayName("구독 취소된 사용자는 다시 구독을 취소할 수 없다.")
+    void alreadyUnsubscribed() {
+        Subscribe subscribe = createSubscribe();
+        subscribe.unsubscribe();
+
+        assertThatThrownBy(subscribe::unsubscribe)
+                .isInstanceOf(IllegalStateException.class)
+                .hasMessage("이미 구독이 취소되었습니다.");
+    }
+
+    private Subscribe createSubscribe() {
+        return new Subscribe("atom@test.com", QuestionCategory.BACKEND, SubscribeFrequency.DAILY);
+    }
+}