jQuery feature

controllers.application\.js

import Controller from '@ember/controller';
import $ from 'jquery'; 

export default Controller.extend({

  init(){
    this._super(...arguments);
    
     alert(Ember.$());
  }

})

templates.application\.hbs

<h1>jQuery - Optional feature </h1>
<br>
<br>
{{outlet}}
<br>
<br>

tests.test-helper\.js

import Application from '../app';
import config from '../config/environment';
import { setApplication } from '@ember/test-helpers';
import { assign } from '@ember/polyfills';
import { start } from 'ember-qunit';

let attributes = {
  rootElement: '#test-root',
  autoboot: false
};
attributes = assign(attributes, config.APP);

let application = Application.create(attributes);
setApplication(application);

start();

twiddle\.json

{
  "version": "0.17.1",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true 
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    
    "ember": "3.11.1", 
"jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
	"ember-template-compiler": "3.11.1",
    "ember-testing": "3.11.1"
  },
  "addons": {
    "@glimmer/component": "1.0.0"
  }
}