groovy - UnsupportedOperationException when using Method Pointer Operator and MockFor -

i had test. using mockfor , working , happy. until changed , forced use method pointer operator, , happiness memory.

here constricted example of problem

import groovy.mock.interceptor.*  // testing againts interface, not actual class // not negociable. interface person {     void sayhello(name); }  // setup (can whatever need) def personmock = new mockfor(person) personmock.demand.sayhello { name -> println "hello $name" } def person = personmock.proxyinstance() // end setup  // exercise (can not change) def closuremethod = person.&sayhello.curry("groovy!") closuremethod() // end exercise  personmock.verify(person) 

which safest , simplest way fix test? currently, test fails java.lang.unsupportedoperationexception

even when testing against interface, nothing prevents me creating mock class implements interface , poor-men verify demands.

import groovy.mock.interceptor.*  // testing against interface, not actual class // not negociable. interface person {     void sayhello(name); }  class personmock implements person {     def calls = []     void sayhello(name) { calls << "sayhello" } }  // setup (can whatever need) def person = new personmock() // end setup  // exercise (can not change) def closuremethod = person.&sayhello.curry("groovy!") closuremethod() // end exercise  assert person.calls == ['sayhello']