how to unit test internal functions in jquery plugin?

plugin.js

// Define global Test object. You can leave this out in production.
Test = Test || {};

(function($) {

  var someHelperFunction = function(s, d) {
    return s*d;
  }
  var someOtherHelperFunction = function(s) {
    return s*2;
  }

  // here goes the normal plugin code

  if(typeof Test !== 'undefined') {
    Test.myPlugin.someHelperFunction = someHelperFunction;
    Test.myPlugin.someOtherHelperFunction = someOtherHelperFunction;
  }
})(jQuery);