Rxjs: How to get immediate subscription result using VirtualTimeScheduler

[wclr]

Trying to implement immediate subscription result using VirtualTimeScheduler:

RxJS version:
5.0.0.beta.11
Code to reproduce:

import {Observable as O, VirtualTimeScheduler} from 'rxjs'

let scheduler = new VirtualTimeScheduler();
let a$ = O.interval(1000, scheduler).map(a => 'a' + a)
let b$ = O.interval(250, scheduler).map(b => 'b' + b)
let c$ = O.merge(a$, b$).take(10)
  .subscribe((x) => console.log(x))
scheduler.flush()

Expected behavior:
Probably should be (this is the output without using virtual scheduler):
b0
b1
b2
a0
b3
b4
b5
b6
a1
b7

Actual behavior:
Actual output:
b0
b1
b2

Additional information:
Can be tried here
http://www.webpackbin.com/4k5VDUM5Z

[kwonoj]

This is because by default virtualTimeScheduler limits maximum frames to be executed.

Internally, virtualTimeScheduler specifies 'frame time factor' to 10 then sets maximum frame to 750 . So in above code snippet, only b$ can be included in those time frame by b$ emitted per 250, 500.. while a$ exceeds it from first emission.

For immediate workaround, I've amended snippet bit (http://www.webpackbin.com/E12aigmqb),

let scheduler = new VirtualTimeScheduler();
+//picked any suffeciently large number can include all frames expected to be executed
+scheduler.maxFrames = 75000;
let a$ = O.interval(1000, scheduler).map(a => 'a' + a);

by setting sufficiently large number of max frame to be allowed which can be done via ctor of scheduler as well.

[kwonoj]

Obviously this seems bit unergonomic, maybe revising interface bit more strictly to give notion to users would be better like

//maxFrame need to be set per each instance creation
constructor(public maxFrames: number, SchedulerAction: typeof AsyncAction = VirtualAction) 

or vice versa. (or simply set default to positive infinity?)

[wclr]

or simply set default to positive infinity?

Why not? =)

[kwonoj]

Why not? =)

: Maybe, maybe not - I'm just not 100% sure if there's reasonable background history of choosing specific number as max frames. I'll leave this issue opened for further discussion.

[benlesh]

This is a bug. The TestScheduler should be limited to a specific window of time.. but the VirtualTimeScheduler should not.

[lock[bot]]

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.