One major pain at testing with culerity so far was a HtmlUnit bug that causes a ScriptException with PUT AJAX requests in jQuery. When you tried to test an update you got a "java.lang.IllegalArgumentException: The content cannot be null". Fortunately, this bug is fixed now. With latest HtmlUnit build culerity should run fine, and I tell you how.
I assume you have culerity installed already. If not, follow these instructions for testing Rails apps or these for testing Couchapps.