Angular6 -如何测试是否应用了[ngClass]？

import { ComponentFixture, TestBed } from '@angular/core/testing';
import { By } from '@angular/platform-browser';

it('should apply [ngClass]', () => {
  // 创建组件
  const fixture = TestBed.createComponent(YourComponent);
  const component = fixture.componentInstance;

  // 执行变更检测
  fixture.detectChanges();

  // 获取包含[ngClass]的元素
  const element = fixture.debugElement.query(By.css('.your-element-class'));

  // 断言判断是否应用了[ngClass]
  expect(element.nativeElement.classList.contains('your-ngclass')).toBe(true);
});