Angularjs unit testing - ng-disabled not working when adding text to textarea

Question

I am trying to test an AngularJS component using karma, mocha, power-assert. I have a textarea and a button in my component, where the button is disabled based on the length of text in textarea.

When I run the component in browser it works perfectly. But I can't figure out how to test this functionality.

Here's a bit of code.

inquiryForm.js

function inquiryForm($scope) {
  // i plan to add some logic here
}
angular.module('myApp').component('inquiryForm', {
  controller: inquiryForm,
  controllerAs: 'inquiryForm',
  templateUrl: 'inquiryForm.html'
});

inquiryForm.html

<div class="contact">
    <div>Thanks for contacting us.</div>
    <form>
        <textarea ng-model="inquiryForm.inquiryText" name=""></textarea>
        <input type="submit" value="SEND" ng-disabled="!inquiryForm.inquiryText.length">
    </form>
</div>

inquiryFormTest.js

describe('inquiry form ', () => {
  let $rootScope;
  let $scope;
  let $compile;
  let element;

  beforeEach(() => {
    angular.mock.module('myApp');

    inject(($injector) => {
      $rootScope = $injector.get('$rootScope');
      $scope = $rootScope.$new();
      $compile = $injector.get('$compile');
    });
  });

  const compileDirective = () => {
    element = $compile('<inquiry-form></inquiry-form>')($scope);
    $scope.$digest();
  };

  describe('inquiry form', () => {
    beforeEach(() => {
      compileDirective();
    });

    // this test passes
    it('disables the submit button if textbox is empty', () => {
      assert(element.find('input').prop('disabled'), true);
    });

    // this test fails
    it('enables the submit button if textbox is not empty', () => {
      // making some changes to DOM here
      element.find('textarea').text('hello, world!');
      console.log(element.find('textarea').text()); // expected: "hello, world!", actual: "hello, world!"

      // since the state of scope has changed, I call digest to reflect those 
      $scope.$digest();

      // this assert passes
      assert(element.find('textarea').text(), 'hello, world!');

      // this one fails.
      assert(element.find('input').prop('disabled'), false);
    });
  });
});

As you can see in the comments above, the second test fails. I am guessing the test has failed since the state of html has not been reflected to the component controller inquiryForm. Sure the DOM of textarea is being updated, but the ng-disabled directive does not trigger since component controller inquiryForm is not connected to the scope.

How can I make this ng-disabled fire with mock user input in textarea...

Answer 1

After lots of searching and trial and error, I have finally found the solution. As I was guessing, the changing of text in textarea was not being communicated to the component controlller hence the ng-disabled="!inquiryForm.inquiryText.length" which contains the reference to it was not triggering.

Here is how I changed my test code...

// this test fails
it('enables the submit button if textbox is not empty', () => {
  // making some changes to DOM here
  // ↓---↓ REMOVED THIS
  // element.find('textarea').text('hello, world!');
  // ↑---↑ this was just making changes to DOM but was not informing the component controller of those changes.

  // ↓+++↓ ADDED THIS
  angular.element(element.find('textarea')).val('hello, world!').triggerHandler('change');
  // ↑+++↑ I used the .val() and .triggerHandler() of angularjs to inform component of changes in state of scope

  // since the state of scope has changed, I call digest to init the watchers 
  $scope.$digest();

  // now this assert passes
  assert(element.find('input').prop('disabled') === false);
});

reference: https://stackoverflow.com/a/26376249/6573907