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 MUC Airport Workshop: Migrating Java Client (Swing / Java FX) to Web Standards
Airport MUC workshops: Web (SPA, PWAs, Offline, Desktop, Mobile) Applications Essentials and Effective Web Applications. No migrations. #usetheplatform
Podcast: airhacks.fm and newsletter: airhacks.news
A book about rethinking Java EE Patterns