fix(debounceTime): unschedule dangling task on unsubscribe before complete

[backbone87]

Description:

Since debounceTime is not based on debounce anymore (#6049), the "notifier subscription" is not managed within the parent subscription anymore, but scheduled "raw". We need to make sure we dont leave dangling tasks behind.

I am not sure how to test this.

edit: this also prevents stopped notifications, if the source errors, because that could also leave dangling tasks behind

[cartant]

I think it would be 'more correct' to add the scheduled action - activeTask - to subscriber. As to how this should be tested I'll have a think about it.

[backbone87]

didnt notice that this was possible, i pushed a version, where the activeTask subscription is managed within the outer subscriber

[cartant]

It ought to be possible to test this using the asyncScheduler's actions property, as is done here (with the animationFrameScheduler):

rxjs/spec/schedulers/AnimationFrameScheduler-spec.ts

Lines 107 to 110 in 3d251be

	expect(animationFrame.actions.length).to.equal(2);
	action1.unsubscribe();
	action2.unsubscribe();
	expect(animationFrame.actions.length).to.equal(0);

[cartant]

This change is fine, but this needs a test that's fixed by the change.

[backbone87]

test added (and verified that it is failing without the fix)

[cartant]

LGTM. Thanks.

[benlesh]

Thank you, @backbone87