loading substate and transition.abort()

router.js

import EmberRouter from '@ember/routing/router';
import config from './config/environment';

const Router = EmberRouter.extend({
  location: 'none',
  rootURL: config.rootURL
});

Router.map(function() {
  this.route('route-with-loading-state');
  this.route('route-aborting-transition');
  this.route('route-aborting-transition-with-loading-state');
});

export default Router;

routes.route-aborting-transition-with-loading-state.js

import Ember from 'ember';
import { later } from '@ember/runloop';
import { Promise } from 'rsvp';

export default Ember.Route.extend({
  async beforeModel(transition) {
    await new Promise((resolve) => {
      later(resolve, 200);
    });
    transition.abort();
  }
});

routes.route-aborting-transition.js

import Ember from 'ember';

export default Ember.Route.extend({
  beforeModel(transition) {
    transition.abort();
  }
});

routes.route-with-loading-state.js

import Ember from 'ember';
import { later } from '@ember/runloop';
import { Promise } from 'rsvp';

export default Ember.Route.extend({
  async beforeModel() {
    await new Promise((resolve) => {
      later(resolve, 200);
    });
  },
  afterModel() {
    this.transitionTo('index');
  }
});

templates.application-loading.hbs

<p>LOADING...</p>

{{#link-to "index"}}Go back to index{{/link-to}}

templates.application.hbs

<h1>loading substate and transition.abort()</h1>

<p>
  Lets first verify that loading substate is working. {{#link-to "route-with-loading-state"}}This link{{/link-to}} triggers a transition to a route that stays a few hundert milliseconds in beforeModel hook and redirects to index route afterwards.
</p>
<p>
	{{#link-to "route-aborting-transition"}}This link{{/link-to}} transitions you to a route which immediatley aborts the transition. Please notice that you don't see loading substate.
</p>
<p>
	{{#link-to "route-aborting-transition-with-loading-state"}}This link{{/link-to}} transitions you to a route which also aborts the transition but stays a few hundert milliseconds in beforeModel hook before. Please notice that you see transition substate.
</p>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "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"
  }
}