Sometimes, you might see errors in your log's application because of something going wrong with your persistence storage. The first thing to do in that case, is to check if the database is up and running by testing its connection; you may even realize that you are pointing to a wrong one or you misspelled the connection URL.
This recipe is based on the previous one, where we have configured a datasource which connects to a local MySQL database, so we will test our database connection with the WildFlyCookBookDS datasource. You can test the connection with a datasource of your choice as long as you provide the correct configuration as well.