Angular unit test mock constant

I have a directive that look like this:

.directive('myScroll', ['$compile','Config', function($compile,Config){
    return {
        scope: true, 
        link: function(scope, element) {
            if(Config.showscroll){
                element.attr('slimscroll', "{'height':menuheight,'alwaysVisible':true}"); 
                element.removeAttr('my-scroll'); 
                $compile(element)(scope);
            }
        }
    };
}]);

The Config is an Angular constant. How can I do the testing by mocking that constant?