Test: trucos para acceder a recursos en los test

(sacado del ejemplo de hibernate caveatemptor-jpa-061211)

testsuite-integration-ejb3.xml:

<!-- DBUnit needs a database connection -->
<parameter name="jndi_datasource" value="java:/caveatemptorTestingDatasource">

<!-- How do we get an EntityManagerFactory from JNDI in tests? -->
<parameter name="jndi_name_emf" value="java:/EntityManagerFactories/caveatEmptorEMF">

<!-- How do we get a JTA UserTransaction from JNDI in tests? -->
<parameter name="jndi_name_usertx" value="UserTransaction">