@Repository
@Transactional(readOnly = true)
public class BookRepositoryJpa implements BookRepository {

    @PersistenceContext
    private EntityManager em;

    @Transactional // тест проходит, даже если я забуду @Transactional - как это проверить?
    public void delete(Book book) {
      em.remove(book);
    }
}


@DataJpaTest
@ComponentScan("my.package.jpa")
class BookRepositoryJpaTest {
    @Autowired
    BookDao bookDao;

    @Autowired
    TestEntityManager tem;

    @Test
    void testDelete() {
        Book bookToDelete = tem.find(Book.class, BOOK2.getBookId());

        bookDao.delete(bookToDelete);
        assertThat(bookDao.findAll()).containsExactly(BOOK5, BOOK4, BOOK3, BOOK1);
    }
}