在Angular 7- Karma中如何期待空的反应形式

import { ComponentFixture, TestBed, fakeAsync, tick } from '@angular/core/testing';
import { MyComponent } from './my.component';

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

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

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

  it('should expect empty response', fakeAsync(() => {
    // 模拟异步操作
    const promise = new Promise((resolve) => {
      setTimeout(() => {
        resolve();
      }, 1000);
    });

    // 执行异步操作
    component.someAsyncMethod();

    // 等待异步操作完成
    tick(1000);

    // 期望空的反应形式
    expect(component.response).toBeUndefined();
  }));
});