Evgenii Evgenii - 1 year ago 88
AngularJS Question

How to trigger ng-change in directive test in AngularJS

I have the following AngularJS directive that creates an

element. Input has
attribute that runs
function. In my directive's unit test I want to check if
function is called when users changes the input. But the test does not pass. Though it works in the browser when testing manually.


template: "<input ng-model='myModel' ng-change='doIt()' type='text'>"


el.find('input').trigger('change') // Dos not trigger ng-change

Live demo (ng-change): http://plnkr.co/edit/0yaUP6IQk7EIneRmphbW?p=preview

Now, the test passes if I manually bind
event instead of using

template: "<input ng-model='myModel' type='text'>",
link: function(scope, element, attrs) {
element.bind('change', function(event) {

Live demo (manual binding): http://plnkr.co/edit/dizuRaTFn4Ay1t41jL1K?p=preview

Is there a way to use
and make it testable? Thank you.

Answer Source

From your explanatory comment:

All I want to do in directive's test is to check that doIt is called when user changes the input.

Whether or not the expression indicated by ng-change is correctly evaluated or not is really the responsibility of the ngModel directive, so I'm not sure I'd test it in this way; instead, I'd trust that the ngModel and ngChange directives have been correctly implemented and tested to call the function specified, and just test that calling the function itself affects the directive in the correct manner. An end-to-end or integration test could be used to handle the full-use scenario.

That said, you can get hold of the ngModelController instance that drives the ngModel change callback and set the view value yourself:

it('trigger doIt', function() {
  var ngModelController = el.find('input').controller('ngModel');

As I said, though, I feel like this is reaching too far into ngModel's responsibilities, breaking the black-boxing you get with naturally composable directives.

Example: http://plnkr.co/edit/BaWpxLuMh3HvivPUbrsd?p=preview


After looking around at the AngularJS source, I found that the following also works:

it('trigger doIt', function() {

It looks like the event is different in some browsers; input seems to work for Chrome.

Example: http://plnkr.co/edit/rbZ5OnBtKMzdpmPkmn2B?p=preview

Here is the relevant AngularJS code, which uses the $sniffer service to figure out which event to trigger:

changeInputValueTo = function(value) {
  browserTrigger(inputElm, $sniffer.hasEvent('input') ? 'input' : 'change');

Even having this, I'm not sure I'd test a directive in this way.