@Test
public void Academy여러개를_joinFetch로_가져온다() throws Exception {

    //given
    List<Academy> academies = academyRepository.findAllJoinFetch();
    List<String> subjectNames = academyService.findAllSubjectNamesByJoinFetch();
    //then
    assertThat(academies.size(), is(20)); // 20개가 조회!?
    assertThat(subjectNames.size(), is(20)); // 20개가 조회!?
}