[BE] FIX: user blackhole same 로직 null 경우 추가

backend/src/main/java/org/ftclub/cabinet/user/domain/User.java

@@ -148,10 +148,21 @@ public boolean isBlackholed() {
 		return blackholedAt != null && blackholedAt.isBefore(LocalDateTime.now());
 	}
 
+	/**
+	 * this.blackholedAt과 전달인자 blackholedAt 중 어느 하나가 null인 경우 false를 반환
+	 *
+	 * @param blackholedAt
+	 * @return
+	 */
 	public boolean isSameBlackholedAt(LocalDateTime blackholedAt) {
+		if (this.blackholedAt == null || blackholedAt == null) {
+			return this.blackholedAt == null && blackholedAt == null;
+		}
+
 		return this.blackholedAt.isEqual(blackholedAt);
 	}
 
+
 	public void addCoin(Long reward) {
 		this.coin += reward;
 	}

backend/src/test/java/org/ftclub/cabinet/user/domain/UserTest.java

@@ -1,10 +1,35 @@
 package org.ftclub.cabinet.user.domain;
 
+import java.time.LocalDateTime;
 import lombok.RequiredArgsConstructor;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
 
 @RequiredArgsConstructor
 public class UserTest {
 
+	@Test
+	void isSameBlackholedAt_test_both_null() {
+		User test = User.of("test", "[email protected]", null);
+		boolean sameBlackholedAt = test.isSameBlackholedAt(null);
+		Assertions.assertTrue(sameBlackholedAt);
+	}
+
+	@Test
+	void isSameBlackholedAt_test_one_null() {
+		User test = User.of("test", "[email protected]", null);
+		boolean sameBlackholedAt = test.isSameBlackholedAt(LocalDateTime.now());
+		Assertions.assertFalse(sameBlackholedAt);
+	}
+
+	@Test
+	void isSameBlackholedAt_test_same() {
+		LocalDateTime now = LocalDateTime.now();
+		User test = User.of("test", "[email protected]", now);
+		boolean sameBlackholedAt = test.isSameBlackholedAt(now);
+		Assertions.assertTrue(sameBlackholedAt);
+	}
+
 //	@Test
 //	@DisplayName("유저 생성 성공 - 일반적인 이메일 형식")
 //	void of_성공_일반적인_이메일_형식() {