Assert In Render

components.my-component\.js

import Component from '@ember/component';
import { assert } from '@ember/debug';
import { later } from '@ember/runloop';

export default Component.extend({
  foo: null,
  
  init() {
    this._super(...arguments);
    
    this.set('foo', ['foo']);
    
    this.prom.then(() => {
      this.set('foo', ['bar']);
    });
  },
  
  didReceiveAttrs() {
    this._super(...arguments);
    
    assert('this fails', false);
  }
});

controllers.application\.js

import Controller from '@ember/controller';

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

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
<br>
<MyComponent />
<br>
{{outlet}}
<br>
<br>

templates.components.my-component\.hbs

{{#each this.foo as |item|}}
  {{item}}
{{/each}}

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

import { module, test } from 'qunit';
import { setupRenderingTest } from 'ember-qunit';
import { render, setupOnerror } from '@ember/test-helpers';
import hbs from 'htmlbars-inline-precompile';
import { Promise } from 'rsvp';

module('Asserting Component', function(hooks) {
  setupRenderingTest(hooks);

  test('Asserts on didReceiveAttrs', async function(assert) {
    assert.expect(1);
    
    let resolved = false;
    
    this.prom = new Promise((resolve, reject) => {
      this.resolve = resolve;
    });
    
    setupOnerror((e) => {
      assert.ok(e.message.includes('this fails'), 'message fail works');
      
      if (!resolved) {
        this.resolve();
        
        resolved = true;
      }
    });

    await render(hbs`{{my-component prom=prom}}`);
  });
});

tests.test-helper\.js

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

let attributes = {
  rootElement: '#test-root',
  autoboot: false
};
attributes = assign(attributes, config.APP);

let application = Application.create(attributes);
setApplication(application);

start();

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": true
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.16.7",
    "ember-template-compiler": "3.16.7",
    "ember-testing": "3.16.7"
  },
  "addons": {
    "@glimmer/component": "1.0.0",
    "ember-data": "3.16.5"
  }
}