How to Unit Test Isolated Scope Directive in AngularJS

What is a good way to unit test isolated scope in AngularJS

JSFiddle showing unit test

Directive snippet

    scope: {name: '=myGreet'},
    link: function (scope, element, attrs) {
        //show the initial state
        greet(element, scope[attrs.myGreet]);

        //listen for changes in the model
        scope.$watch(attrs.myGreet, function (name) {
            greet(element, name);

I want to ensure the directive is listening for changes - this does not work with an isolated scope:

    it('should watch for changes in the model', function () {
        var elm;
        spyOn(scope, '$watch');
        elm = compile(validHTML)(scope);
        expect(scope.$watch).toHaveBeenCalledWith('name', jasmine.any(Function));

UPDATE: I got it to work by checking if the expected watchers were added to the child scope, but it's very brittle and probably using the accessors in an undocumented way (aka subject to change without notice!).

//this is super brittle, is there a better way!?
elm = compile(validHTML)(scope);

UPDATE 2: As I mentioned this is brittle! The idea still works but in newer versions of AngularJS the accessor has changed from scope() to isolateScope():

//this is STILL super brittle, is there a better way!?
elm = compile(validHTML)(scope);