重构 Observable 以避免类型断言错误

Question

我正在为 CanDeactive Guard 编写单元测试，但我的 jasmine 规范出现类型断言错误：

// Mock Guard defined at top of spec file
class MockGuardComponent implements ComponentCanDeactivate {
  // Set this value to the value you want to mock being returned from 
GuardedComponent
  returnValue: boolean | Observable<boolean>;

  canDeactivate(): boolean | Observable<boolean> {
    return this.returnValue || this.openConfirmDialog();
  }
}

it('will not route if guarded and user rejected the dialog', () => {
    // Mock the behavior of the MockGuardedComponent
    const subject$ = new Subject<boolean>();
    mockGuardComponent.returnValue = subject$.asObservable();
    const canDeactivate$ = <Observable<boolean>>(
      service.canDeactivate(mockGuardComponent)
    );
    canDeactivate$.subscribe((deactivate) => {
      // this is the real test
      expect(deactivate).toBeFalsy();
    });
    // Emulate the reject
    subject$.next(false);

}。 );

此规范正确抛出以下错误：

Type assertion using the '<>' syntax is forbidden. Use the 'as' syntax instead.

不喜欢这部分：

<Observable<boolean>>

我知道使用 BehaviorSubject 可能会更好，但我已经在使用 Subject 所以我不确定如何结合我正在做的事情这里。有什么建议吗？

Answer 1

改变

const canDeactivate$ = <Observable<boolean>>(
      service.canDeactivate(mockGuardComponent)
    );

到

const canDeactivate$ = service.canDeactivate(mockGuardComponent) as Observable<boolean>;