Item's member function names sometimes are not found and get "Uncaught exception: foobar is not defined" error

import QtQuick 2.0
import QtTest 1.0
   TestCase {
       id:testCase
       function test_stack() {
           var limit = 125;
           for (var i = limit-1; i > 0; --i)
           {
               console.log("i=" + i);
               compare(1, 1);
               //testCase.compare(1, 1); //this always works
           }
       }
 }