Unit test $ formatters in Angular directive

I have a simple validator that checks the input against a regular expression:

.directive('test', function () {
return {
    restrict: 'A',
    require: 'ngModel',
    link: function ($scope, element, attrs, ctrl) {

        ctrl.$setValidity('namePattern', true);

        function checkValid(name) {
            console.log('checkValid executed');
            if (!name || ctrl.$pristine) {
                ctrl.$setValidity('namePattern', true);
                return name;
            }
            var test = /^[A-Za-z0-9_-]+$/;
            ctrl.$setValidity('namePattern', test.test(name));
            return name;
        }

        // called when value changes via code/controller
        ctrl.$formatters.unshift(checkValid);
        // called when value changes in input element
        ctrl.$parsers.unshift(checkValid);
    }
  };
});

      

        
        
        
      

    

Live example

I want to unit test this directive and have this:

function initState() {
  angular.mock.module('app');
  angular.mock.inject(function($compile, $rootScope, $timeout){
    $scope = $rootScope.$new();

    $rootScope.safeApply = function(cb) {
      $timeout(function() {
        $scope.$digest();
      });
    };

    $scope.model = {
      instanceName: ''
    };

    var tmpl = angular.element('<form name="form">' +
      '<input ng-model="model.instanceName" name="instanceName" test>' +
      '</form>'
    );

    element = $compile(tmpl)($scope);
    $scope.$apply();
    form = $scope.form;
  });
}
beforeEach(initState);

      

        
        
        
      

    

However, changes to the model do not trigger checkValid

. I tried to directly set the property on the model:

it('should trigger a change resulting in an invalid state', function () {
  $scope.model.instanceName = 'this is an invalid name';
  $scope.$digest();
  expect(form.instanceName.$valid).to.be.false;
});

      

        
        
        
      

    

as well as neutralization using $modelValue

:

it('should trigger a change resulting in an invalid state', function () {
  form.instanceName.$modelValue = 'this is an invalid name';
  $scope.$digest();
  expect(form.instanceName.$valid).to.be.false;
});

      

        
        
        
      

    

I also tried to fire the event input

via element.triggerHandler

.

How can I force the model change to be checkValid

executed through $formatters

?

(Angular 1.2.23 used)