Class CustomIdleService

packages/core/test/acceptance/defer_spec.ts:2110–2131

      };

      @Injectable({providedIn: 'root'})
      class CustomIdleService implements IdleService {
        private callbacks: Array<((deadline?: IdleDeadline) => void) | undefined> = [];

        requestOnIdle(
          callback: (deadline?: IdleDeadline) => void,
          options?: IdleRequestOptions,
        ): number {
          return this.callbacks.push(callback) - 1;
        }

        cancelOnIdle(id: number): void {
          this.callbacks[id] = undefined;
        }

        trigger(): void {
          for (const callback of this.callbacks) {
            callback?.();
          }
          this.callbacks.length = 0;
        }
      }

      TestBed.configureTestingModule({
        providers: [