Run ngrx/effect outside of Angular's zone to prevent timeout in Protractor

Question

I just started to write e2e tests for my app and am running into timeout problems with Protractor and ngrx/effects.

I have the following effect dispatching an action ev

Answer 1

For Angular 6 and RxJS 6 use the following code:

import { SchedulerLike, Subscription } from 'rxjs'
import { NgZone } from '@angular/core'

class LeaveZoneScheduler implements SchedulerLike {
  constructor(private zone: NgZone, private scheduler: SchedulerLike) { }

  schedule(...args: any[]): Subscription {
    return this.zone.runOutsideAngular(() =>
      this.scheduler.schedule.apply(this.scheduler, args)
    )
  }

  now (): number {
    return this.scheduler.now()
  }
}

class EnterZoneScheduler implements SchedulerLike {
  constructor(private zone: NgZone, private scheduler: SchedulerLike) { }

  schedule(...args: any[]): Subscription {
    return this.zone.run(() =>
      this.scheduler.schedule.apply(this.scheduler, args)
    )
  }

  now (): number {
    return this.scheduler.now()
  }
}

export function leaveZone(zone: NgZone, scheduler: SchedulerLike): SchedulerLike {
  return new LeaveZoneScheduler(zone, scheduler)
}

export function enterZone(zone: NgZone, scheduler: SchedulerLike): SchedulerLike {
  return new EnterZoneScheduler(zone, scheduler)
}

The effect should look like:

import { asyncScheduler } from 'rxjs'
import { filter, observeOn, bufferTime } from 'rxjs/operators'
import { enterZone, leaveZone } from './util';

actions$.ofType('[Light] Turn On')
  .pipe(
    bufferTime(300, leaveZone(this.ngZone, asyncScheduler)),
    filter(messages => messages.length > 0),
    observeOn(enterZone(this.ngZone, asyncScheduler)),
  )

Answer 2

The solution is to schedule the timer observable to run outside of NgZone and then re-enter the zone when something interesting occurs.

First you are going to need two utility functions that wrap any scheduler and cause the effect to enter or leave the zone:

import { Subscription } from 'rxjs/Subscription';
import { Scheduler } from 'rxjs/Scheduler';
import { NgZone } from '@angular/core';


class LeaveZoneSchduler {
  constructor(private zone: NgZone, private scheduler: Scheduler) { }

  schedule(...args: any[]): Subscription {
    return this.zone.runOutsideAngular(() => 
        this.scheduler.schedule.apply(this.scheduler, args)
    );
  }
}

class EnterZoneScheduler {
  constructor(private zone: NgZone, private scheduler: Scheduler) { }

  schedule(...args: any[]): Subscription {
    return this.zone.run(() => 
        this.scheduler.schedule.apply(this.scheduler, args)
    );
  }
}

export function leaveZone(zone: NgZone, scheduler: Scheduler): Scheduler {
  return new LeaveZoneSchduler(zone, scheduler) as any;
}

export function enterZone(zone: NgZone, scheduler: Scheduler): Scheduler {
  return new EnterZoneScheduler(zone, scheduler) as any;
}

Then using a scheduler (like asap or async) you can cause a stream to enter or leave the zone:

import { async } from 'rxjs/scheduler/async';
import { enterZone, leaveZone } from './util';

actions$.ofType('[Light] Turn On')
    .bufferTime(300, leaveZone(this.ngZone, async))
    .filter(messages => messages.length > 0)
    .observeOn(enterZone(this.ngZone, async))

Note that most of the time-based operators (like bufferTime, debounceTime, Observable.timer, etc) already accept an alternative scheduler. You only need observeOn to re-enter the zone when something interesting happens.