Angular单元测试--如何获得覆盖容器中的子组件

import { ComponentFixture, TestBed } from '@angular/core/testing';
import { ParentComponent } from './parent.component';
import { ChildComponent } from './child.component';

describe('ParentComponent', () => {
  let component: ParentComponent;
  let fixture: ComponentFixture<ParentComponent>;

  beforeEach(async () => {
    await TestBed.configureTestingModule({
      declarations: [ParentComponent, ChildComponent]
    })
    .compileComponents();
  });

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

  // 进行测试...
});

it('should get child components', () => {
  const childComponents = fixture.debugElement.queryAll(By.directive(ChildComponent));
  expect(childComponents.length).toBeGreaterThan(0);
});

it('should get the first child component', () => {
  const firstChildComponent = fixture.debugElement.query(By.directive(ChildComponent));
  expect(firstChildComponent).toBeTruthy();
});