test(util): BCryptPasswordEncoderUtil 인스턴스화 테스트 추가

- private 생성자를 이용한 인스턴스화 불가능 여부 테스트 추가
- UnsupportedOperationException 예외 발생 확인

Author: m-a-king

src/test/java/com/somemore/global/util/encoder/BCryptPasswordEncoderUtilTest.java

@@ -1,9 +1,12 @@
 package com.somemore.global.util.encoder;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
-import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.lang.reflect.InvocationTargetException;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 class BCryptPasswordEncoderUtilTest {
 
@@ -33,4 +36,18 @@ void testMatches() {
         // then
         assertThat(BCryptPasswordEncoderUtil.matches(rawPassword, encodedPassword)).isTrue();
     }
+
+    @Test
+    @DisplayName("인스턴스화 할 수 없다.")
+    void testConstruct() throws Exception {
+        // given
+        var constructor = BCryptPasswordEncoderUtil.class.getDeclaredConstructor();
+        constructor.setAccessible(true);
+
+        // when & then
+        assertThatThrownBy(constructor::newInstance)
+                .isInstanceOf(InvocationTargetException.class)
+                .extracting(Throwable::getCause)
+                .isInstanceOf(UnsupportedOperationException.class);
+    }
 }