How to test $on event with parameters in Karma

I have the controller code:

  $scope.$on('load', function (event) {
  $scope.getData();
  event.stopPropagation();
});

and the test code:

 it('$on load', function(event) {
        var controller=createController();
        spyOn(scope, '$on').andCallThrough();// I have also tried to spy scope getData
        scope.$broadcast('load');
        expect(scope.$on).toHaveBeenCalledwith("load");

 });

TypeError: event.stopPropagation is not a function

How can I define the parameters in the call from the Unit test?