Mocking Firestore collection in angular TestBed

Ok, I finally have managed mocking of Firestore collections. I give an example of different service:

SUT

import { Injectable } from '@angular/core';
import { AngularFirestore } from 'angularfire2/firestore';
import { Administrative } from '../model/administrative';

@Injectable()
export class AdministrativeService {

  administratives: Administrative[] = [];

  constructor(private db: AngularFirestore) {
   this.db.collection<Administrative>('administrative').valueChanges()
    .subscribe(data => this.administratives = data);
  }

  getPath(uname: string): string[] {
    let current = this.administratives.find((a: Administrative) => a.uname === uname);
    const result: string[] = [current.name];

    while (current.parent) {
      current = this.administratives.find((a: Administrative) => a.uname === current.parent);
     result.unshift(current.name);
    }

    return result;
  }
}

TEST

import { TestBed, inject } from '@angular/core/testing';
import { AdministrativeService } from './administrative.service';
import { AngularFirestore } from 'angularfire2/firestore';
import { Observable } from 'rxjs/Rx';
import { Administrative } from '../model/administrative';

const input: Administrative[][] = [[
  { name: 'Polska', uname: 'polska', parent: ''},
  { name: 'Dolnośląskie', uname: 'dolnoslaskie', parent: 'polska'},
  { name: 'Wrocław', uname: 'wroclaw', parent: 'dolnoslaskie'}
]];

const data = Observable.from(input);

const collectionStub = {
  valueChanges: jasmine.createSpy('valueChanges').and.returnValue(data)
}

const angularFiresotreStub = {
  collection: jasmine.createSpy('collection').and.returnValue(collectionStub)
}

describe('AdministrativeService', () => {
  let service: AdministrativeService;
  let angularFirestore: AngularFirestore;

  beforeEach(() => {
    TestBed.configureTestingModule({
      providers: [
        AdministrativeService,
        { provide: AngularFirestore, useValue: angularFiresotreStub }
      ]
    });

    service = TestBed.get(AdministrativeService);
    angularFirestore = TestBed.get(AngularFirestore);
  });

  it('should be created', () => {
    expect(service).toBeTruthy();
    expect(angularFiresotreStub.collection).toHaveBeenCalledWith('administrative');
  });

  it('gets hierarchy path', () => {
    const result = service.getPath('wroclaw');
    expect(result).toEqual(['Polska', 'Dolnośląskie', 'Wrocław']);
  });

});