hibernate-demo/src/test/java/com/ankurm/hibernatedemo/jndi/HibernateJndiDataSourceTest.java

package com.ankurm.hibernatedemo.jndi;

import static org.assertj.core.api.Assertions.assertThat;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NameAlreadyBoundException;
import org.h2.jdbcx.JdbcDataSource;
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Backs docs/10-mocking-jndi-datasources.md, chapter "Getting Hibernate itself to resolve a JNDI DataSource by
 * name". Deliberately bypasses Spring Boot's autoconfiguration entirely and goes straight at
 * Hibernate's own {@code hibernate.connection.datasource} setting (see
 * {@code org.hibernate.cfg.JdbcSettings.DATASOURCE} -- confirmed present in 7.4.5.Final via
 * javap, docs/output/jndi-hibernate-datasource-setting-javap.txt), which is the exact mechanism
 * the article's original code was trying to exercise through Spring.
 *
 * <p>A separate attempt to get Spring Boot's own {@code spring.datasource.jndi-name} property
 * to resolve through a full {@code @SpringBootTest} context (with {@code spring-boot-starter-web}
 * on the test classpath and {@code simple-jndi}'s {@code MemoryContextFactory}) reproduced a
 * {@code NameNotFoundException} at Spring bean-creation time that this test's plain-Hibernate
 * bootstrap does not hit at all -- see the findings report for what was and was not diagnosed
 * about that gap. This test is the one that stayed green and demonstrates the real mechanism:
 * a JNDI-bound {@code DataSource}, resolved by name, driving a working {@code SessionFactory}.
 */
class HibernateJndiDataSourceTest {

    private static final Logger DEMO = LoggerFactory.getLogger("DEMO");
    private static final String JNDI_NAME = "jdbc/HibernateTestDS";

    @BeforeEach
    void bindDataSource() throws Exception {
        System.setProperty(Context.INITIAL_CONTEXT_FACTORY, "org.osjava.sj.MemoryContextFactory");
        System.setProperty("org.osjava.sj.jndi.shared", "true");

        JdbcDataSource ds = new JdbcDataSource();
        ds.setURL("jdbc:h2:mem:hibernate-jndi-test;DB_CLOSE_DELAY=-1");
        ds.setUser("sa");
        ds.setPassword("");

        Context ctx = new InitialContext();
        createSubcontextIfAbsent(ctx, "jdbc");
        ctx.rebind(JNDI_NAME, ds);
    }

    @AfterEach
    void unbindAndClearFactory() throws Exception {
        try {
            new InitialContext().unbind(JNDI_NAME);
        } catch (Exception ignored) {
        }
        System.clearProperty(Context.INITIAL_CONTEXT_FACTORY);
        System.clearProperty("org.osjava.sj.jndi.shared");
    }

    // Real-world hygiene, discovered the hard way: simple-jndi's shared MemoryContext is a
    // single JVM-wide namespace. If a DIFFERENT test class in the same run already created the
    // "jdbc" subcontext and did not tear it down, a plain createSubcontext("jdbc") here throws
    // NameAlreadyBoundException before this test even gets to the DataSource bind -- this is
    // the exact cross-test pollution CrossTestPollutionTest demonstrates on purpose, caught
    // here by accident the first time this suite ran as a whole rather than one class at a time.
    private static void createSubcontextIfAbsent(Context ctx, String name) throws Exception {
        try {
            ctx.createSubcontext(name);
        } catch (NameAlreadyBoundException alreadyThere) {
            // fine -- another test in this JVM already created it
        }
    }

    @Test
    void hibernateResolvesDataSourceByJndiName_andBuildsAWorkingSessionFactory() {
        StandardServiceRegistry registry = new StandardServiceRegistryBuilder()
                .applySetting("hibernate.connection.datasource", JNDI_NAME)
                .applySetting("hibernate.hbm2ddl.auto", "create-drop")
                .build();

        try {
            SessionFactory sessionFactory = new Configuration().buildSessionFactory(registry);

            assertThat(sessionFactory).isNotNull();
            try (var session = sessionFactory.openSession()) {
                Integer result = session.createNativeQuery("SELECT 1", Integer.class).getSingleResult();
                DEMO.info("Hibernate SessionFactory built from JNDI name '{}' ran SELECT 1 -> {}", JNDI_NAME, result);
                assertThat(result).isEqualTo(1);
            } finally {
                sessionFactory.close();
            }
        } finally {
            StandardServiceRegistryBuilder.destroy(registry);
        }
    }
}