SmartBear released Ready API which is further enhancement to SoapUI Pro (both are paid tools) which has context sense help while doing groovy scripting.
And the following link might be helpful to scripting.
Also would like to add a point that in groovy script test step, the following instance variables are available as you would see the same on the groovy script panel, top of the editor.
- context
- log
- testRunner
And the small tip is that if you type log.info in the script, you can see some interesting stuff in the log.
For example you can try
log.info testRunner