public void deleteCommentById(final Long memberId, final Long commentId) {
        Comment comment = findComment(commentId);
        comment.validateWriterId(memberId);

        commentRepository.deleteById(commentId);
    }
@Test
    void 글쓴이가_아니라면_댓글을_삭제하지_못한다() {
        // given
        commentRepository.save(댓글_생성());

        // when & then
        assertThatThrownBy(() -> commentService.deleteCommentById(2L, 1L))
                .isInstanceOf(CommentWriterNotEqualsException.class);
    }