Input but test

components.my-component\.js

import Component from '@glimmer/component';
import { tracked } from '@glimmer/tracking';
import { action } from '@ember/object';

export default class extends Component {
  @tracked value = '';
  @tracked counter = 0;

  @action submit() {
    this.counter += 1;
  }
}

controllers.application\.js

import Controller from '@ember/controller';


export default class ApplicationController extends Controller {
  appName = 'Ember Twiddle';
}

templates.application\.hbs

<MyComponent />

templates.components.my-component\.hbs

<p>Value: {{this.value}}</p>
<p>Enter pressed: {{this.counter }} time(s)</p>

<p>
  Broken Input with @enter={this.submit}<br/>
  <Input @value={{this.value}} @enter={{this.submit}} placeholder="Press Enter"/>
</p>
<p>
  Works Input with @enter={fn this.submit}<br/>
  <Input @value={{this.value}} @enter={{fn this.submit}} placeholder="Press Enter" />
</p>
<p>
  Works Input with @enter={action this.submit}<br/>
  <Input @value={{this.value}} @enter={{fn this.submit}} placeholder="Press Enter" />
</p>
<p>
  Works Input with @enter="submit"<br/>
  <Input @value={{this.value}} @enter="submit" placeholder="Press Enter" />
</p>

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": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.18.1",
    "ember-template-compiler": "3.18.1",
    "ember-testing": "3.18.1"
  },
  "addons": {
    "@glimmer/component": "1.0.0"
  }
}