ember-test-action

components.my-component.js

import Ember from 'ember';

export default Ember.Component.extend({
  x: 5,
  
  actions:{
    incrementX(){
      this.set('x', this.get('x') + 1);
      this.get("someAction")();
    }
  }
  
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  actions: {
    someAction() {
      // does something
    },
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
{{my-component someAction=(action "someAction")}}
<br>
{{outlet}}
<br>
<br>

templates.components.my-component.hbs

x = {{x}}
<button onclick={{action "incrementX"}} >incrementx</button>

tests.integration.components.my-component-test.js

import { moduleForComponent, test } from 'ember-qunit';
import hbs from 'htmlbars-inline-precompile';

moduleForComponent('my-component', 'TODO: put something here', {
  integration: true
});

test('it renders', function(assert) {

  // Set any properties with this.set('myProperty', 'value');
  // Handle any actions with this.on('myAction', function(val) { ... });
  const someActionSpy = function(){};
  this.set('someAction', someActionSpy);
  this.render(hbs`{{my-component someAction=(action someAction)}}`);

  assert.ok(this.$().text());
	const button = this.$('button');
  button.click();
});

tests.test-helper.js

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

let attributes = assign({ rootElement: '#main' }, config.APP);
setApplication(Application.create(attributes));

start();

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": true
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}