ember-unit-testing-components.js

gistfile1.txt

// test helper
import { getContext } from '@ember/test-helpers';

export default function createComponent(lookupPath, named = {}) {
  let { owner } = getContext();
  let componentManager = owner.lookup('component-manager:glimmer');
  let { class: componentClass } = owner.factoryFor(lookupPath);
  return componentManager.createComponent(componentClass, { named });
}

// In your test
const component = createGlimmerComponent('component:my-component');

assert.equal(
  component.getId(stuff),
  'expectedId',
  'returns expected id'
);

Why components, in many cases, should avoid unit testing.

From Ben Demboski

...Components don't really have a Javascript API. Like, no Javascript code besides Ember/glimmer internals should ever have a reference to the component object. So the API it makes the most sense to test is the one exposed via the DOM/templates, and then interactions with services via injections, which are fully available using rendering tests.

The advice that I've heard is that if you have any really in-depth logic that is isolated from the DOM/templates/arguments and from injected services, then you should put that in a utility function and unit test that utility function, because by definition it's not logic that is tightly coupled with the component-ness of your component.