added simple integration test for hds-register-event

packages/components/src/modifiers/hds-register-event.js

@@ -9,7 +9,7 @@ import { modifier } from 'ember-modifier';
 // see: https://github.com/emberjs/ember.js/issues/19869#issuecomment-1909118910
 // see: https://github.com/emberjs/ember.js/pull/20629
 // see also: https://github.com/emberjs/ember.js/blob/main/packages/%40ember/-internals/glimmer/lib/modifiers/on.ts#L30
-export default modifier((element, positional, named) => {
+export default modifier((element, positional, named = {}) => {
   // the "target" element the listeners are added to
   // notice: this is the element the Ember modifier is attached to
   const targetElement = element;
@@ -19,7 +19,7 @@ export default modifier((element, positional, named) => {
   // the options for the `addEventListener()` method
   // see: https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener
   // notice: it's expressed as "named" argument (object) for the modifier
-  const { useCapture = false } = named ?? {};
+  const { useCapture = false } = named;
 
   targetElement.addEventListener(event, eventHandler, useCapture);
 

showcase/tests/integration/modifiers/hds-register-event-test.js

@@ -0,0 +1,23 @@
+/**
+ * Copyright (c) HashiCorp, Inc.
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
+import { module, test } from 'qunit';
+import { setupRenderingTest } from 'ember-qunit';
+import { click, render } from '@ember/test-helpers';
+import { hbs } from 'ember-cli-htmlbars';
+
+module('Integration | Modifier | hds-register-event', function (hooks) {
+  setupRenderingTest(hooks);
+
+  test('it calls the callback associated with the `click` event assigned via the modifier', async function (assert) {
+    let clicked;
+    this.set('onClick', () => (clicked = true));
+    await render(
+      hbs`<button id="test-button" {{hds-register-event 'click' this.onClick}}>Test</button>`
+    );
+    await click('button#test-button');
+    assert.true(clicked);
+  });
+});