Unit-testing an Angular Controller's initialization function

I am faced with what is I believe a very straightforward scenario, but I cannot find a clear answer: I have a controller which does a number of things when created, including somewhat complicated stuff, and so I have created an initialization function to do it.

Here's what the controller code looks like:

function MyCtrl() {
    function init() {
            // do stuff
    }
    var vm = this;
    vm.init = init;
    vm.init();
}

Obviously, I want to unit test init(), but I cannot find a way to do so: when I instanciate the controller in my tests, init() is run once, which makes it hard to correctly test its side-effects when I run it a second time.

I'm using karma-jasmine for the tests, and usually do something like this:

describe('Controller: MyCtrl', function () {
    var myCtrl;
    beforeEach(angular.mock.module('myApp'));
    beforeEach(inject(function ($controller, $rootScope) {
        $scope = $rootScope.$new();
        createController = function () {
            return $controller('MyCtrl', {$scope: $scope});
        };
    }));
    it('bleh', function() {
        myCtrl = createController();
        // init has already been run at that point
    });
)};

Again, I'm sure it's really straightforward and I'm simply missing the point, but I'm still fairly new to Angular. Thanks a lot for your help!