Angularfire -如何测试$watch回调？

import { TestBed, async } from '@angular/core/testing';
import { AngularFireDatabase } from '@angular/fire/database';

describe('MyComponent', () => {
  let component: MyComponent;
  let firebaseDatabase: AngularFireDatabase;

  beforeEach(async(() => {
    TestBed.configureTestingModule({
      providers: [AngularFireDatabase]
    }).compileComponents();
  }));

  beforeEach(() => {
    firebaseDatabase = TestBed.inject(AngularFireDatabase);
    component = new MyComponent(firebaseDatabase);
  });

  it('should call the $watch callback when data changes', () => {
    const callbackSpy = spyOn(component, 'callback');
    const testData = { key: 'value' };

    // 模拟数据变化
    firebaseDatabase.object('path').next(testData);

    expect(callbackSpy).toHaveBeenCalledWith(testData);
  });
});