SimpleNamingContextBuilder builder = SimpleNamingContextBuilder.emptyActivatedContextBuilder();
DataSource ds = new DriverManagerDataSource();
builder.bind("java:comp/env/jdbc/MyDB", ds);
PersistenceUnitReader reader = new PersistenceUnitReader(
new PathMatchingResourcePatternResolver(), new JndiDataSourceLookup());
String resource = "/org/springframework/orm/jpa/persistence-example4.xml";
PersistenceUnitInfo[] info = reader.readPersistenceUnitInfos(resource);
assertNotNull(info);
assertEquals(1, info.length);