RxJs lastValueFrom scheduled asapScheduler strange behaviour

[nigrosimone]

Describe the bug

I have this stript for play with scheduled/asapScheduler but I found a strange behaviour in combination with lastValueFrom:

    import { of, lastValueFrom, scheduled, asapScheduler } from 'rxjs';
    
    const bbj = { foo: 'bar' };
    
    async function foo() {
      const result = await lastValueFrom(scheduled(of(bbj), asapScheduler));
      console.log(result);
      return result;
    }
    
    async function main() {
      await foo(); // 1° console log
      await foo(); // 2° console log
      await foo(); // 3° console log
    }
    
    document.getElementById('button').addEventListener('click', function () {
      main();
    });

the expected behaviour is on button click, 3 console log, eg.:

{foo: "bar"}
{foo: "bar"}
{foo: "bar"}

But on first click it produce NO console log

On second click it produce 5 console log:

{foo: "bar"}
{foo: "bar"}
{foo: "bar"}
{foo: "bar"}
{foo: "bar"}

and on third click, 1 console log:

{foo: "bar"}

Why not produce 3 console log on each click?

Expected behavior

3 console log on each click

{foo: "bar"}
{foo: "bar"}
{foo: "bar"}

Reproduction code

import { of, lastValueFrom, scheduled, asapScheduler } from 'rxjs';
    
    const bbj = { foo: 'bar' };
    
    async function foo() {
      const result = await lastValueFrom(scheduled(of(bbj), asapScheduler));
      console.log(result);
      return result;
    }
    
    async function main() {
      await foo(); // 1° console log
      await foo(); // 2° console log
      await foo(); // 3° console log
    }
    
    document.getElementById('button').addEventListener('click', function () {
      main();
    });

Reproduction URL

try online https://stackblitz.com/edit/rxjs-mkgftu?devtoolsheight=60&file=index.ts

Version

7

Environment

No response

Additional context

No response

[voliva]

It could be an issue on scheduled with synchronous values. It looks like for some reason on the first click the observable emits the value, but it doesn't complete the observable.

https://stackblitz.com/edit/rxjs-cwwznh?devtoolsheight=60&file=index.ts

[voliva]

I think this was fixed by #7198, not released yet as a patch.

I've bisected it by adding this test:

it('completes', (done) => {
    const input = of('a');
    scheduled(input, asapScheduler).subscribe({
      complete: done
    });
  });

on master and 7.x branch it's fixed, and before that merge it breaks.

[benlesh]

This is confirmed fixed in the latest published version of RxJS (7.8.1)