Behavior of `delay` inconsistent with completions.

[benlesh]

Currently, delay will delay the completion notification, but only if there is no nexted value (the source is "empty").

This just doesn't make any sense. It should either always delay notification of complete, or it shouldn't.

Personally, I think it should not delay notification of complete, given that it's a composable behavior that way. The other way it's not, it's hard to remove the delay once it's added, because it's more obscured from downstream consumers (outside of some crazy mulitcasting scenario)

[benlesh]

Core team agrees this should be fixed.

[martinsik]

It seems like the complete notification is always delayed right now. https://stackblitz.com/edit/rxjs-uxspew

delaying complete when source is empty:
https://github.com/ReactiveX/rxjs/blob/master/spec/operators/delay-spec.ts#L101-L109

delaying complete after next notifications:
https://github.com/ReactiveX/rxjs/blob/master/spec/operators/delay-spec.ts#L25-L36

If I understand it correctly delay should delay complete only if there're already scheduled values. Otherwise situations like of(1, 2, 3).pipe(delay(500)) would never emit anything because complete would be sent immediately before any of the values are reemitted. So in this case it'll wait until all scheduled values are reemitted and them complete.
If there are no scheduled values it can complete immediately after receiving complete from source.