1. 게시글 목록보기 쿼리 만들기 JPQL

public List<Board> findAll(){
    Query query = em.createQuery("select b from Board b order by b.id desc", Board.class);
    return query.getResultList();
}

2. 게시글 목록보기 단위 테스트

@Test
public void findAll_test() {
    // given

    // when
    List<Board> boardList = boardPersistRepository.findAll();

    // then
    System.out.println("findAll_test/size : " + boardList.size());
    System.out.println("findAll_test/username : " + boardList.get(2).getUsername());

    // org.assertj.core.api
    assertThat(boardList.size()).isEqualTo(4);
    assertThat(boardList.get(2).getUsername()).isEqualTo("ssar");
}

3. 컨트롤러 수정