I am in the process of unit testing a DAO built with Spring/JPA and Hibernate as the provider.

Prior to running the test, DBUnit inserted a User record with username "poweruser" -- username is the primary key in the users table. Here is the integration test method:

@Test
@ExpectedException(EntityExistsException.class)
public void save_UserTestDataSaveUserWithPreExistingId_EntityExistsException() {
    User newUser = new UserImpl("poweruser");

    newUser.setEmail("[email protected]");
    newUser.setFirstName("New");
    newUser.setLastName("User");
    newUser.setPassword("secret");

    dao.persist(newUser);
}

I have verified that the record is in the database at the start of this method. Not sure if this is relevant, but if I do a dao.flush() at the end of this method I get the following exception:

javax.persistence.PersistenceException: org.hibernate.exception.ConstraintViolationException: 
    Could not execute JDBC batch update