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Testing Controllers

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Unit testing methods and computed properties follows previous patterns shown in Unit Testing Basics because Ember.Controller extends Ember.Object.

Unit testing controllers is very simple using the unit test helper which is part of the ember-qunit framework.

Testing Controller Actions

Here we have a controller PostsController with some computed properties and an action setProps.

You can follow along by generating your own controller with ember generate controller posts.

app/controllers/posts.js
export default Ember.Controller.extend({
  propA: 'You need to write tests',
  propB: 'And write one for me too',

  setPropB(str) {
    this.set('propB', str);
  },

  actions: {
    setProps(str) {
      this.set('propA', 'Testing is cool');
      this.setPropB(str);
    }
  }
});

setProps sets a property on the controller and also calls a method. In our generated test, ember-cli already uses the moduleFor helper to setup a test container:

tests/unit/controllers/posts-test.js
moduleFor('controller:posts', {
});

Next we use this.subject() to get an instance of the PostsController and write a test to check the action. this.subject() is a helper method from the ember-qunit library that returns a singleton instance of the module set up using moduleFor.

tests/unit/controllers/posts-test.js
test('should update A and B on setProps action', function(assert) {
  assert.expect(4);

  // get the controller instance
  const ctrl = this.subject();

  // check the properties before the action is triggered
  assert.equal(ctrl.get('propA'), 'You need to write tests', 'propA initialized');
  assert.equal(ctrl.get('propB'), 'And write one for me too', 'propB initialized');

  // trigger the action on the controller by using the `send` method,
  // passing in any params that our action may be expecting
  ctrl.send('setProps', 'Testing Rocks!');

  // finally we assert that our values have been updated
  // by triggering our action.
  assert.equal(ctrl.get('propA'), 'Testing is cool', 'propA updated');
  assert.equal(ctrl.get('propB'), 'Testing Rocks!', 'propB updated');
});

Testing Controller Needs

Sometimes controllers have dependencies on other controllers. This is accomplished by injecting one controller into another. For example, here are two simple controllers. The CommentsController uses the PostController via inject:

You can follow along by generating your own controller with ember generate controller post, and ember generate controller comments.

app/controllers/post.js
export default Ember.Controller.extend({
  title: Ember.computed.alias('model.title')
});
app/controllers/comments.js
export default Ember.Controller.extend({
  post: Ember.inject.controller(),
  title: Ember.computed.alias('post.title')
});

This time when we setup our moduleFor we need to pass an options object as our third argument that has the controller's needs.

tests/unit/controllers/comments-test.js
moduleFor('controller:comments', 'Comments Controller', {
  needs: ['controller:post']
});

Now let's write a test that sets a property on our post model in the PostController that would be available on the CommentsController.

tests/unit/controllers/comments-test.js
test('should modify the post model', function(assert) {
  assert.expect(2);

  // grab an instance of `CommentsController` and `PostController`
  const ctrl = this.subject();
  const postCtrl = ctrl.get('post');

  // wrap the test in the run loop because we are dealing with async functions
  Ember.run(function() {

    // set a generic model on the post controller
    postCtrl.set('model', Ember.Object.create({ title: 'foo' }));

    // check the values before we modify the post
    assert.equal(ctrl.get('title'), 'foo', 'title is set');

    // modify the title of the post
    postCtrl.get('model').set('title', 'bar');

    // assert that the controllers title has changed
    assert.equal(ctrl.get('title'), 'bar', 'title is updated');
  });
});
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