Add resetOnerror from @ember/test-helpers

[scalvert]

This PR is paired with the new @ember/test-helpers API (setupOnerror/resetOnerror) for providing an Ember.onerror implementation (emberjs/ember-test-helpers#548). This adds automatic wiring up of resetOnerror with mocha's root module afterEach, so we ensure that the Ember.onerror function is reset after each test.

[rwjblue]

On the surface, the CI failure seems unrelated. I’ll trigger a master build to confirm.

[rwjblue]

Running here:
https://travis-ci.org/emberjs/ember-mocha/builds/487906773

[scalvert]

Ya I don't really understand the failure. It appears to imply that we need to use the async done callback, but I'm not sure why. resetOnerror is sync, so I don't understand what's happening.

I'm going to debug a bit to understand.

[scalvert]

OK, so updated the code to not pass resetOnerror as a ref to afterEach. This seems to have addressed the issue.

function setupResetOnerror() {
  afterEach(function() {
    resetOnerror();
  });
}

[rwjblue]

Ya, that makes sense. Mocha checks function arity to decide if it needs to pass in and wait on the done callback.

[Turbo87]

thanks :)