You test webservices using Groovy code with the argoservice Tester view, available from Administration Debug
argoservice Tester
argoservice Tester view.
For Groovy plug-ins: Use the groovy-script test.
For Code Extensions: Use the groovy-extension test.
For N4 2.5 and later, Navis updated the open source library from Groovy WS to Groovy-WSlite (because Groovy WS is not supported on Java 7). If you are on N4 2.5, you must migrate your code to Groovy-WSlite.