Use Shift+Cmd+T (or Alt+Cmd+T for current daily builds) to switch between the production class and the related unit test.
If it doesn't work, you probably forgot to write a test (it happens sometimes :-))
See you at Java EE Workshops at MUC Airport (March 25th-28th)!
NEW online workshop: WebStandards Igniter (online)
Airport MUC workshops: Java EE 7: Bootstrap, Effective, Architectures, Web, React and Angular, Testing and Microservices
A book about rethinking Java EE Patterns