Observable.concat() does not complete with a buffered scalar observable

[emonkak]

This Observable does not complete.

const { Observable } = Rx

Observable
  .create(observer => {
    setTimeout(function() {
      observer.next(1)
      observer.complete()
    }, 1000)
    })
  .concat(Observable.of(2))
  .subscribe(
    x => console.log('Next:', x),
    x => console.log('Error:', x),
    () => console.log('Completed')
  )

http://jsfiddle.net/bo6ynqf7/7/

Expected:

Next: 1
Next: 2
Complete

Actual:

Next: 1
Next: 2

[niklasfasching]

Concat is based on mergeAll-support, which does not subscribe to scalar-observables but instantly nexts their value. However, for notifyComplete to be called, the observable has to be subscribed to by an innerSubscriber.

It can be resolved by simply removing the check & subscribing to non-scalar & scalar observables alike. I.e.

_next(observable: any) {
  if (this.active < this.concurrent) {
    this.active++;
    this.add(subscribeToResult<T, R>(this, observable));
  } else {
    this.buffer.push(observable);
  }
}

But I don't know if that's the best solution...

[kwonoj]

Thinking this might be another side effect of ScalarObservable, related to #1142.

[trxcllnt]

@Nupf yes, subscribeToResult already handles ScalarObservable, so any operators that check for _isScalar and aren't using subscribeToResult should be refactored to always call subscribeToResult.

[benlesh]

@kwonoj @trxcllnt ... do you know if this is still an issue?

[kwonoj]

Just tried again with TOT and seems it's still occurring.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.