For the first test, no exception gets propagated when thrown in the before completion phase. This behaviour is the same with the JBOSS transaction manager...

While there is some JBossTS logging, that is not the JTA system you are using there. Just look at the stack trace. You are using some Spring-specific JTA platform (org.springframework.transaction.support.AbstractPlatformTransactionManager).

This is why we ask people to move Spring out of the way. Its not because we hate Spring; its because the environment is too complex to determine where the issue is. If the test is just Hibernate, JBossTS and your db that's much easier to figure out.