如何在Angular 6中测试app/root组件

import { ComponentFixture, TestBed } from '@angular/core/testing';
import { AppComponent } from './app.component';

beforeEach(async () => {
  await TestBed.configureTestingModule({
    declarations: [AppComponent],
    // 导入其他模块（如果有）
  }).compileComponents();
});

beforeEach(() => {
  fixture = TestBed.createComponent(AppComponent);
  component = fixture.componentInstance;
});

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

it('should render title', () => {
  const compiled = fixture.nativeElement;
  expect(compiled.querySelector('h1').textContent).toContain('My App');
});