hibernate-demo/src/test/java/com/ankurm/hibernatedemo/proxy/OpenInViewAndLazyLoadNoTransTest.java

package com.ankurm.hibernatedemo.proxy;

import static org.assertj.core.api.Assertions.assertThat;
import static org.junit.jupiter.api.Assertions.assertThrows;

import jakarta.persistence.EntityManager;
import jakarta.persistence.EntityManagerFactory;
import org.hibernate.LazyInitializationException;
import org.hibernate.Session;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.TestPropertySource;

/**
 * Backs docs/11-proxies-and-lazy-initialization.md, chapter "hibernate.enable_lazy_load_no_trans: does it still exist?".
 *
 * <p>{@code org.hibernate.cfg.TransactionSettings.ENABLE_LAZY_LOAD_NO_TRANS} still resolves to
 * the constant string {@code hibernate.enable_lazy_load_no_trans} in Hibernate 7.4.5.Final --
 * confirmed by {@code javap} on the jar (see docs/output/proxy-settings-javap.txt). It is NOT
 * removed. It IS annotated {@code @org.hibernate.cfg.Unsafe}, a marker interface with no members
 * that Hibernate's own codebase uses to flag settings the team does not want you reaching for.
 * This test proves the setting still functionally does something in 7.4.5: with it enabled, a
 * lazy proxy can be touched after its own originating transaction/session has ended, because
 * Hibernate opens a temporary session behind the scenes to service exactly that one lazy load.
 */
@SpringBootTest
@TestPropertySource(properties = {
        "spring.jpa.properties.hibernate.enable_lazy_load_no_trans=true"
})
class OpenInViewAndLazyLoadNoTransTest {

    private static final Logger DEMO = LoggerFactory.getLogger("DEMO");

    @Autowired
    private EntityManagerFactory emf;

    @Test
    void withEnableLazyLoadNoTrans_toOneProxyInitializesAfterSessionCloses_viaTemporarySession() {
        EntityManager seedEm = emf.createEntityManager();
        seedEm.getTransaction().begin();
        ProxyPublisher publisher = new ProxyPublisher("No-Trans Press");
        seedEm.persist(publisher);
        ProxyBook book = new ProxyBook("No-Trans Book", publisher);
        seedEm.persist(book);
        seedEm.getTransaction().commit();
        Long id = book.getId();
        seedEm.close();

        EntityManager em = emf.createEntityManager();
        em.getTransaction().begin();
        Session session = em.unwrap(Session.class);
        ProxyBook proxy = session.getReference(ProxyBook.class, id);
        em.getTransaction().commit();
        em.close();

        // No exception here: with enable_lazy_load_no_trans=true, Hibernate 7.4.5 opens a
        // temporary session to service this access instead of throwing.
        String title = proxy.getTitle();
        DEMO.info("enable_lazy_load_no_trans=true: proxy.getTitle() after close returned '{}' with no exception", title);
        assertThat(title).isEqualTo("No-Trans Book");
    }
}