Sometimes (often :-)) it is hard to say whether just the application or the whole application server is not working. Also debugging JNDI configuration may be challenging.
ping is a simplistic 5kb WAR which exposes JNDI, system properties and "echo" service through REST APIs.
Download the WAR. Source code is available at github: https://github.com/AdamBien/ping/
See you at Java EE Workshops at MUC Airport, particularly at: Effective Java EE 7!
NEW online workshop: WebStandards Igniter (online)
Airport MUC workshops: Java EE 8, Java 9: Bootstrap, Effective, Architectures, Single Page Apps, Progressive Web Apps, HTML 5, ES 6, CSS 3 and Microservices
Podcast: airhacks.fm and newsletter: airhacks.news
A book about rethinking Java EE Patterns