I am trying to write a Qunit test for a javascript closure function (testQUnit) using sinon library for mocking and spying on the function but it is not able to spy on the below closure.

Closure function:

var testQUnit = (function() {
  return {
    script :{
      test1 : function(){
        console.log('test');
      }
    }
  }
})();

Test1 :

QUnit.test( "testQUnit", sinon.test(function( assert ) {

 var returnScript= testQUnit.script;
    var spy = this.spy(returnScript,'test1');

  testQUnit.scripts.test1();
    assert(spy.callCount,1);

}));

Error: Died on test #1 undefined: [object Object] is not a function.

Test2 :

QUnit.test( "testQUnit", sinon.test(function( assert ) {

  //var returnScript= testQUnit.script;
    var spy = this.spy(testQUnit,'script.test1');

  testQUnit.scripts.test1();
    assert(spy.callCount,1);

}));

Error: Died on test #1 undefined: Attempted to wrap undefined property script.test1 as function.