angular - 如何使用角度测试 ngx-bootstrap 模态

Question

在我使用@Output() 发出后，我尝试测试我的 toHaveBeenCalled 函数"@angular/core": "~12.2.0"，"ngx-bootstrap": "^7.1.0"

这是我的代码
主要组件：

showModal() {
    this.modalRef = this.modalService.show(MyModalComponent);
    this.modalRef.content.emitBack.subscribe((response: Boolean) => {
      if (response) {
        this.mySimpleFunction();
      }
    });
  }

模态组件：

@Output() emitBack = new EventEmitter();

constructor(private modalService: BsModalService) { }

ngOnInit() {
}

closeModal() {
    this.modalService.hide();
    this.emitBack.emit(true);
}

我想期待mySimpleFunction();被叫
，但我得到了TypeError: Cannot read properties of undefined (reading 'content')

这是我的单元测试：

describe('showModal', () => {
  let component: MyMainComponent;
  let modalService: BsModalService;

  beforeEach(() => {
    modalService = jasmine.createSpyObj('BsModalService', ['hide', 'show']);
    component = new DocumentComponent(modalService);
  });

  it('should call function after modal close', () => {
    component.modalRef = modalService.show(MyModalComponent);
    spyOn(component.modalRef.content, 'emitBack');
    component.showModal();
    expect(component.mySimpleFunction).toHaveBeenCalled();
  });
});