Testing DAO and Service / Spring

The question has already been asked at Stackoverflow but I haven't found the answer. I can't understand how to test (unit) my DAO and Service layers (you will be able to find the methods I would like to test below). So, there are two opposite notions regarding testing of DAO: the one is not to test it at all, the opposite one is to test it only with in-memory DB. As for service layer there are meaning that method should be tested only if it has business logic. So, frankly I can't even imaging what to do because I'm not sure which the way is correct. At my last pet project I tested DAO by using jUnit only (examle for saveEntity()): I explicitly created entity, populated it, saved it by using DAO-method, when retrieved it, asserted result and explicitly deleted the object from the DB. I'm sure that it is not the proper way to test it. So, please take a look at the code below and give me an advice how to test these layers' methods properly:

DAO

@Override
public void saveEntity(Artist entity) throws ConstraintViolationException {
    sessionFactory.getCurrentSession().save(entity);
}

Service

@Transactional
@Override
public void saveEntity(Artist entity) throws ConstraintViolationException {
    artistDAO.saveEntity(entity);
}

I wanted to do it with Mockito but all examples I found not similar to my case. Thank you for any ideas how to do that.