[SpringBoot] No EntityManager with actual transaction available for current thread

❗️ 에러문구
No EntityManager with actual transaction available for current thread - cannot reliably process 'persist' call
jakarta.persistence.TransactionRequiredException: No EntityManager with actual transaction available for current thread - cannot reliably process 'persist' call at app//org.springframework.orm.jpa

⭐️ entityManager를 통한 모든 데이터 변경은 항상 transaction 안에서 이루어져야 한다!!

💡 에러 해결 방법
테스트 코드에 @Transactional넣기

	@Test
    @Transactional
    @Rollback(value = false)
    public void testMember() throws Exception {
        //given
        Member member = new Member();
        member.setUsername("memberA");

        //when
        Long savedId = memberRepository.save(member);
        Member findMember = memberRepository.find(savedId);

        //then
        Assertions.assertThat(findMember.getId()).isEqualTo(member.getId());
        Assertions.assertThat(findMember.getUsername()).isEqualTo(member.getUsername());
    }