finalize not working as expected with streams from dependencies

[cdanielw]

Bug Report

Current Behavior
Given project a and b. When a subscribe to a stream from b, the finalize operator doesn't get called.

The below script outputs:

a finalized c

Reproduction
https://github.com/cdanielw/rxjs-finalize

const {finalize, first} = require('rxjs/operators')
const anotherModule$ = require('b')
const sameModule$ = require('./c')

anotherModule$.pipe(
        // Stream from another module doesn't finalize
	finalize(() => console.log('a finalized b')),
	first()
).subscribe()

sameModule$.pipe(
        // Stream from same module finalize
	finalize(() => console.log('a finalized c')),
	first()
).subscribe()

Expected behavior
Script should output :

a finalized b
a finalized c

Environment

• Runtime: Node v10.14.2
• RxJS version: 6.5.4

[cdanielw]

I managed to workaround it:

of(true).pipe(
    switchMap(() => anotherModule$),
    finalize(() => console.log('1. a finalized b')),
    first()
).subscribe()

But it's easy to forget to do this, leading to subtle bugs.

[cartant]

from(anotherModule$) should be used. I'll write an explanation when I'm less tired. Not a bug, IMO.

[cdanielw]

Having different code depending on how/where code has been required makes it very difficult to pull RxJS code into shared libraries. This is where my issue is coming from.

Even if this wouldn't be considered a bug, I'd really like you to consider removing any differences in behaviour based on where streams/code creating streams have been required from.

[cartant]

Yeah. I was wrong; this is definitely a bug.

I guess I really was tired, last night, as I recently fixed a problem that was closely related to this - see #5059 and the associated cherry pick into v6.

That PR includes testing infrastructure that'll allow me to reproduce your problem in a failing test. After which, I'll fix it.

Thanks for opening the issue.