AngularJS changing controller mocks

I'm using this construct:

Directive with a ControllerAs. The Controller has a depencency on a Service which does REST requests.

The directive and the controller:

angular.module('app')
.directive('thingsList', function () {
    return {
        templateUrl: 'thingsListEntry-template.html',
        restrict: 'A',
        controller: 'thingsListController as ctrl'
    };
})
.controller('thingsListController', function (thingsStorage) {
    thingsStorage.getList().then(angular.bind(this, function (response) {
        this.things = response;
    }));
});

What I want to do now is to test the directive with a controller mock:

describe('things list test suite', function() {

describe('tests for the directive', function () {
    var scope, render, element, mockController;

    /**
     * Mock the controller
     */
    beforeEach(module('app', function ($provide, $controllerProvider) {
        $controllerProvider.register('thingsListController', function () {
            this.things = [];
            mockController = this;
        });
    }));

    beforeEach(inject(function($rootScope, $compile) {
        scope = $rootScope.$new();
        var angularElement = angular.element('<div things-list></div>');
        var compileFunction = $compile(angularElement);
        render = function () {
            element = compileFunction(scope);
            $rootScope.$digest();
        };
    }));

    it('should be empty without things', function() {
        render();
        expect(element[0].querySelectorAll('div.things-list-entry').length).toEqual(0);
    });

What I would like to do next is to change the things in the controller mock and test that. I don't know how to do that

it('should contain 1 entry with 1 thing', function () {
        mockController.things = [{'name':'1'}];
        render();
        expect(element[0].querySelectorAll('div.thing-list-entry').length).toEqual(1);
    });

Here I'm setting mockController.things, but I'm not sure how to get to the mockController. The version above sets it in the mock setup. I also tried using scope.ctrl.things and couple other things but nothing works. Any suggestions?