Testing Spring & Hibernate Without XML

I’m very keen on the improvements in Spring 3 that eventually let you move away from XML into plain Java configuration with proper support from IDE and compiler. It doesn’t change the fact that Spring is a huge suite and it sometimes finding the thing you need can take a while.

XML-free unit tests around Hibernate are one such thing. I knew it was possible, but it took me more than 5 minutes to find all the pieces, so here I am writing it down.

I am going to initialize all my beans in a @Configuration class like this:

@Configuration
@EnableTransactionManagement
public class TestRepositoryConfig {
	@Bean
	public DataSource dataSource() {
		return new EmbeddedDatabaseBuilder().setType(EmbeddedDatabaseType.H2)
				.setName("Nuts").build();
	}

	@Bean
	public LocalSessionFactoryBean sessionFactoryBean() {
		LocalSessionFactoryBean result = new LocalSessionFactoryBean();
		result.setDataSource(dataSource());
		result.setPackagesToScan(new String[] { "pl.squirrel.testnoxml.entity" });

		Properties properties = new Properties();
		properties.setProperty("hibernate.hbm2ddl.auto", "create-drop");
		result.setHibernateProperties(properties);
		return result;
	}

	@Bean
	public SessionFactory sessionFactory() {
		return sessionFactoryBean().getObject();
	}

	@Bean
	public HibernateTransactionManager transactionManager() {
		HibernateTransactionManager man = new HibernateTransactionManager();
		man.setSessionFactory(sessionFactory());
		return man;
	}

	@Bean
	public OrderRepository orderRepo() {
		return new OrderRepository();
	}
}

… and my test can look like this:

@RunWith(SpringJUnit4ClassRunner.class)
@TransactionConfiguration(defaultRollback = true)
@ContextConfiguration(classes = { TestRepositoryConfig.class })
@Transactional
public class OrderRepositoryTest {
	@Autowired
	private OrderRepository repo;

	@Autowired
	private SessionFactory sessionFactory;

	@Test
	public void testPersistOrderWithItems() {
		Session s = sessionFactory.getCurrentSession();

		Product chestnut = new Product("Chestnut", "2.50");
		s.save(chestnut);
		Product hazelnut = new Product("Hazelnut", "5.59");
		s.save(hazelnut);

		Order order = new Order();
		order.addLine(chestnut, 20);
		order.addLine(hazelnut, 150);

		repo.saveOrder(order);
		s.flush();

		Order persistent = (Order) s.createCriteria(Order.class).uniqueResult();
		Assert.assertNotSame(0, persistent.getId());
		Assert.assertEquals(new OrderLine(chestnut, 20), persistent
				.getOrderLines().get(0));
		Assert.assertEquals(new OrderLine(hazelnut, 150), persistent
				.getOrderLines().get(1));
	}
}

There are a few details worth noting here, though:

1. I marked the test @Transactional, so that I can access Session directly. In this scenario, @EnableTransactionManagement on @Configuration seems to have no effect as the test is wrapped in transaction anyway.
2. If the test is not marked as @Transactional (sensible when it only uses @Transactional components), the transaction seems to always be committed regardless of @TransactionConfiguration settings.
3. If the test is marked as @Transactional, @TransactionConfiguration seems to be applied by default. Even if it’s omitted the transaction will be rolled back at the end of the test, and if you want it committed you need @TransactionConfiguration(defaultRollback=false).
4. This probably goes without saying, but the @Configuration for tests is probably different from production. Here it uses embedded H2 database, for real application I would use a test database on the same engine as production.

That’s it, just those two Java classes. No XML or twisted depedencies. Take a look at my github repository for complete code.