A simplified implementation of the ng-hide directive, to illustrate directive testing.

ngHideClone.js

angular.directive('ngHide', [function () {
  return function (scope, element, attr) {
    scope.$watch(attr.ngShow, function ngHideWatchAction(value){
      // Call "addClass()" or "removeClass()" based on the attribute value
      // AngularJS already declares the CSS for the "ng-hide" class
      element[value ? 'removeClass' : 'addClass']('ng-hide');
    });
  };
}]);