test.js

describe('myApp', function () {
  var element, scope, innerScope, elementCtrl;
  beforeEach(function () {
    module('myApp');
    //Create Element with our directive
    element = angular.element('<my-drtv passed-var="passThis" passed-expression="myFunction()">');
   
    inject(function ($rootScope, $compile) {
      scope = $rootScope.$new();
      //Create scope variables to pass to the directive
      scope.passThis = 'Passing';
      scope.myFunction = function(){};
      $compile(element)(scope);
      scope.$digest();
      //Now our element is ready and behaving like it would on a page
      innerScope = element.isolateScope();    
      elementCtrl = innerScope.myDirectiveCtrl;
    });
  });
   
  it('says hello', function () {
    expect(element.text()).toBe('Hello Passing');
  });
   
  it('should call the passed function', function(){
    //Watch our main scope's function
    spyOn(scope,"myFunction");
    expect(scope.myFunction).not.toHaveBeenCalled();
    //Tell the element to call it's function that calls the parent's function
    elementCtrl.doSomething();
    expect(scope.myFunction).toHaveBeenCalled();
  });
 
});