public void validateWriter(final Long memberId) {
        if (!this.writerId.equals(memberId)) {
            throw new WriterNotEqualsException();
        }
    }
@Test
    void 작성자가_아니면_예외를_발생한다() {
        // given
        Board board = 게시글_생성_사진없음();

        // when & then
        assertThatThrownBy(() -> board.validateWriter(board.getWriterId() + 1))
                .isInstanceOf(WriterNotEqualsException.class);
    }