0.2.0: axe.run doesn't polyfill Promise implementation

[Trent Willis]

Since axe.run doesn't polyfill a Promise implementation, if a browser doesn't support Promises natively and the consumer isn't providing a polyfill, things break. This wasn't caught in our test suite since we include the babel polyfill.

[Robert Jackson]

"polyfill" it 😝:

// vendor/ember-a11y-testing/promise-polyfill.js

(function() {
  if (typeof self.Promise === 'undefined') {
    self.Promise = Ember.RSVP.Promise;
  }
})();

Then use app.import('vendor/ember-a11y-testing/promise-polyfill.js', { type: 'test' }); in index.js.

[Robert Jackson]

The app.import above needs to go above the app.import for vendor/axe-core/axe.js.

[Trent Willis]

@rwjblue I have tried something similar to the above, but the issue is that Ember.RSVP.Promise ties into the run-loop. Thus, since we trigger the audit "after render" in the run-loop, we actually wind up with an infinite loop (from what I can tell).

[Trent Willis]

So in trying to fix this, I keep running upon other issues. In particular, changing the implementation from using a Promise to a using callbacks uncovers the fact that we run additional audits during the run-loop when the application is getting destroyed. This is bad, but we have no way to prevent it.

Due to that, the above issue, and other factors, I've opened an issue to remove the auto-run feature, which makes the path forward substantially simpler.

[Trent Willis]

With the removal of auto-run in #64 and the usage of RSVP.Promise for the a11yAudit helper, this should be resolved.