javax.naming.NameNotFoundException: Test_DB not found
Have you deployed your datasource to point to the MySQL database. Here's what that article mentions:
The unit will use a data source with JNDI name jdbc/__default. This data source is automatically defined when Glassfish is installed. In real life, you will probably use a database such as MySQL, Oracle or DB2. In that case, you must first define a data source using the Glassfish administration console.