fix($q): allow third-party promises

[vbraun]

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
For testing, it can be useful to run with other promise
implementations like Bluebird.js + angular-bluebird-promises. This
broke in angularjs 1.6 with a "TypeError: Cannot set property 'pur' of
undefined".

Closes #16164

What is the current behavior? (You can also link to an open issue here)
Raises TypeError: Cannot set property 'pur' of undefined

What is the new behavior (if this is a feature change)?
N/A

Does this PR introduce a breaking change?
No

Please check if the PR fulfills these requirements

• The commit message follows our guidelines
• Fix/Feature: Docs have been added/updated
• Fix/Feature: Tests have been added; existing tests pass

Other information:

[petebacondarwin]

@vbraun - thanks for sending this in.
Have you tested that this then works with Bluebird? I wonder if we could have some kind of tests for this?

[vbraun]

I'm using kriskowal's Q with jsdom for some tests, and I can confirm that it works with that combination. On #16164 the reporter indicated that it works with Bluebird but I haven't confirmed that personally.

Not sure about unit tests, of course one could try various third-party libraries but would be quite some effort... Or just manually delete the q.$$state?

[gkalpak]

We decided it is not worth adding tests for the specific issue that this PR solves, since substituting $q with another promise library is neither thoroughly tested, nor officially supported (although it seems to be possible). So, even if we tested that nothing breaks due to missing $$state, there is still no guarrantee that something else doesn't break.

We can land this as is (with a comment explaining what these lines guard against).

[gkalpak]

Hm...I was going through the code looking for other places that might need fixing and I realized I am not sure why this should be necessary (i.e. where this function would be called from when using a 3rd-party promise library) 😕

Could you share a minimal demo (e.g. plnkr, repo, or live app (with non-minified sources 😁)) that showcases the current failures?

[gkalpak]

It seems like this change is indeed not necessary (relevant discussion).

[davidwilder]

Could you share a minimal demo (e.g. plnkr, repo, or live app (with non-minified sources 😁)) that showcaes the current failures?

We are also using using Bluebird.js + angular-bluebird-promises. Setting ngModelOptions raises the TypeError: Cannot set property 'pur' of undefined. Please find a demo here http://plnkr.co/edit/9oDzLt?p=preview

[gkalpak]

Thx for the reproduction, @davidwilder. Based on the stack trace, the error happens in the markQStateExceptionHandled() method and not isStateExceptionHandled(). As mentioned in #16164 (comment), I don't think isStateExceptionHandled() needs to be changed (but it won't hurt either).

[gkalpak]

Tweaked a bit and merged.

BTW, if anyone can't upgrade to the latest AngularJS version, it is possible to work around this issue by adding a $$state: {} property on the promise prototype. For example, in the case of Bluebird + angular-bluebird-promises (demo):

.config(Bluebird => Bluebird.prototype.$$state = {})