Testing Angular component with api service in OnInit (Spectator)

rest.service.ts

import {HttpClient} from '@angular/common/http';
import {Injectable} from '@angular/core';
import {Observable} from 'rxjs/index';

export interface someObject {
}

@Injectable({
  providedIn: 'root'
})
export class RestService {

  constructor(private http: HttpClient) {
  }

  getAllStuffFromServer(): Observable<Array<SomeObject>> {
    return this.http.get<Array<SomeObject>>(`/api/some/all`);
  }
}

some.component.spec.ts

import {createTestComponentFactory, Spectator} from '@netbasal/spectator';
import {of} from 'rxjs/index';
import {RestService, someObject} from './rest.service';
import {SomeComponent} from './some.component';

describe('SomeComponent', () => {
  const createComponent = createTestComponentFactory({
    component: SomeComponent,
    mocks: [RestService]
  });

  let spectator: Spectator<SomeComponent>;

  beforeEach(() => {
    spectator = createComponent(null, false);

    spectator.get(RestService).getAllStuffFromServer.andReturn(of({}));

    spectator.detectChanges();
  });

  it('should create', () => {
    expect(spectator.component).toBeTruthy();
  });
});

some.component.ts

import {Component, OnInit} from '@angular/core';
import {RestService, SomeObject} from './rest.service';

@Component({
  selector: 'some-component',
  templateUrl: './some.component.html',
  styleUrls: ['./some.component.scss']
})
export class SomeComponent implements OnInit {

  someObjects: Array<SomeObjects>;

  constructor(private restService: RestService) {
  }

  ngOnInit() {
    this.restService.getAllStuffFromServer()
      .subscribe(someObjects => {
        this.someObjects = someObjects;
      });
  }
}