如何测试angular onInit方法中的订阅函数？

import { ComponentFixture, TestBed } from '@angular/core/testing';
import { MyComponent } from './my.component';
import { MyService } from './my.service';
import { of } from 'rxjs';

describe('MyComponent', () => {
  let component: MyComponent;
  let fixture: ComponentFixture<MyComponent>;
  let myService: MyService;

  beforeEach(async () => {
    await TestBed.configureTestingModule({
      declarations: [MyComponent],
      providers: [MyService]
    }).compileComponents();
  });

  beforeEach(() => {
    fixture = TestBed.createComponent(MyComponent);
    component = fixture.componentInstance;
    myService = TestBed.inject(MyService);
  });

  it('should call the subscription function on initialization', () => {
    // Create a spy on the subscription function
    spyOn(myService, 'subscribeFunction').and.returnValue(of('test'));

    // Trigger the onInit method
    component.ngOnInit();

    // Assert that the subscription function was called
    expect(myService.subscribeFunction).toHaveBeenCalled();

    // Assert any other expectations on the behavior of the subscription function
    // For example, you can check if it returned the expected result
    expect(component.someProperty).toBe('test');
  });
});