Unit test spyOn is never called angular factory

I am trying to write a unit test for a angular factory:

define([], function () {
    'use strict';

    var factoryName = 'UserFactory';
    var components = ['ProductFactory', '$state'];

    var factory = function (ProductFactory, $state) {

        var viewState = function(view, data) {
            if(data.access[view] === true) {
                return;
            }
            else {                
                $state.go('notAuth');
            }
        };

        return {
            viewState: viewState
        };
    };

    components.push(factory);

    return {
        name: factoryName,
        component: components
    };
});

I have the following unit test:

define(['require', 'angular-mocks'], function (require) {
    'use strict';

    var angular = require('angular');

    describe('<-- UserFactory Spec ------>', function () {

        var scope, $httpBackend, userFactory;

        beforeEach(angular.mock.module('UserFactory'));

        beforeEach(inject(function (_$rootScope_, _UserFactory_) {
            scope = _$rootScope_.$new();
            userFactory = _UserFactory_;
            spyOn(userFactory, 'viewState').and.returnValue({firstName:'Joe',lastName:'Smith',access:'read'});
            scope.$apply();
        }));


        it('method viewState() was called', function () {
            expect(userFactory.viewState).toHaveBeenCalled();
        });
    });
});

However i see the following error:

Expected spy viewState to have been called.