Which @angular/* package(s) are relevant/related to the feature request?

@angular/core/testing

Description

I'm making use of fakeAsync extensively for my tests and I like the control it gains me, so I want to express my gratitude towards the development and maintenance of this functionality.

I've noticed that the fake async Scheduler has a flush function that exposes a parameter flushPeriodic which allows the caller to flush any periodic tasks as well.

  flush(limit = 20, flushPeriodic = false, doTick?: (elapsed: number) => void): number {
    if (flushPeriodic) {
      return this.flushPeriodic(doTick);
    } else {
      return this.flushNonPeriodic(limit, doTick);
    }
  }

source for this snipper

However, the flush function imported from @angular/core/testing does not make use of that parameter and instead just goes along with the default value.

export function flush(maxTurns?: number): number {
  if (fakeAsyncTestModule) {
    return fakeAsyncTestModule.flush(maxTurns);
  }
  throw new Error(fakeAsyncTestModuleNotLoadedErrorMessage);
}

source for this snippet

I was just wondering if there is a specific reason for this? It would be really helpful to have the ability to pass that to my flush-es as well, instead of having to tick for the periodic tasks.

Proposed solution

I'm not sure it would be so simple as this, but I guess what I'm asking requires a change like so:

export function flush(maxTurns?: number, flushPeriodic = false): number {
  if (fakeAsyncTestModule) {
    return fakeAsyncTestModule.flush(maxTurns, flushPeriodic);
  }
  throw new Error(fakeAsyncTestModuleNotLoadedErrorMessage);
}

Keeping the default value false as to not change anything in the existing implementation.

Alternatives considered

I'd like any possible way to access that particular functionality, to flush, be it a change to the existing function or a new function flushPeriodic that would to exactly that.