Exploring async testing examples with ember-milestones (https://github.com/salsify/ember-milestones)

ember-milestones-examples.js

/**********************************************************************************
** Basic timeout example
**/

// component
export default Component.extend({
  pollStatus: task(function*() {
    yield milestone('poll-status-timeout', () => timeout(1000));
    this.get('statusModel').reload();
  }),
});

// component-test
test('it polls for status updates', async function() {
  const milestones = activateMilestones(['poll-status-timeout']);  
  // ...
  await milestones.advanceTo('poll-status-timeout').andPause();
  assert.equal(this.component.status, 'running');
  milestones.unpause().andReturn();
  // ...
  milestones.deactivate();
});



/**********************************************************************************
** Component example w/ two milestones 
**/

// edit-approval component
export default Component.extend({
  async init() {
    this._super(...arguments);

    await milestone('load-changeset', async () => {
      await this.get('loadChanges').perform();
      this.get('validators').revalidate();
    });
  },

  async _updateAllChanges(properties) {
    const describable = this.get('changeset.targetItem');

    for (const change of this.get('changeset.proposedChanges')) {
      const assignment = describable.assignmentForProperty(get(change, 'propertyId'));

      setProperties(change, {
        ...properties,
        baseLockVersion: get(assignment, 'lockVersion'),
      });
    }

    await milestone('save-changeset', async () => {
      await this.get('saveChanges').perform();
      this.get('validators').revalidate();
    });
  },
})

// edit-approval-test
moduleForComponentPageObject('edit-approval', 'Integration | Component | edit approval', {
  componentPageObject: 'edit-approval',
  integration: true,

  beforeEach() {
    // ...
  },

  afterEach() {
    this.milestones.deactivate();
  },
});

test('it allows proposed changes to be approved', async function(assert) {
  this.milestones = activateMilestones(['load-changeset', 'save-changeset']);

  this.render(hbs`
    {{task-ui-components/edit-approval
      config=config
      env=env
    }}
  `);

  await this.milestones.advanceTo('load-changeset').andContinue();

  assert.notOk(this.get('env.validators').areAllValid());
  this.component.acceptButton.click();
  assert.ok(this.get('env.validators').areAllValid());

  await this.milestones.advanceTo('save-changeset').andContinue();

  this.inject.service('itemRepoStore');

  assert.ok(this.get('itemRepoStore.changeset').save.calledOnce);
  assert.ok(this.get('itemRepoStore.changeset.proposedChanges').every((change) => {
    return change.accepted === true;
  }));
});



/**********************************************************************************
** Notes  
**/

// If you wrap the whole thing, you can't test error handling
// so just wrap the part that can throw an error
loadData: task(function*() {
  try {
    yield milestone('load-data', async () => {
      await this.get('loadTask').perform()
      await this.get('loadPrincipal').perform()
    });
  } catch (e) {
    // error handling
  }
})