我创建了一个html文件与按钮。onClickEvent轮询后出现，下一步，点击按钮后"提交"对话框窗口关闭，我想调用下一个方法。
TS.file:

openDialogWindow() {
const dialogRef = this.dialogWindow.open(PollComponent, {
  width: '400px',
  height: '400px',
  data: getData()
});

dialogRef.afterClosed().subscribe(result => {
  if (result.status == 'VALID') {
    answerForm = result;
    this.callNextFunction();
  }
});

}
然后我在spec. ts文件中创建了单元测试：

it('should call dialogwindow and after submit call methods', () => {
service.callNextFunction.and.returnValue(of({value: 0}));

const result = new FormGroup({}, )
result.setValidators(null);
spyOn(component.dialogWindow, 'open')
  .and
  .returnValue({
    afterClosed: () => of(true)
  } as MatDialogRef<typeof component>);
  
fixture.detectChanges();
expect(component.dialogWindow.afterAllClosed).toContain(result);
expect(service.callNextFunction).toHaveBeenCalled();
expect(component.otherForm.recommendedValue.control.value).toEqual('123');

}）;
但是当我测试它的时候，我得到了错误：

Error: <spyOn> : open has already been spied upon
Usage: spyOn(<object>, <methodName>)

是否由创建引起：

matDialogSpy = createSpyObj<MatDialog>('MatDialog', ['open']);

在beforeEach中？我在其他单元测试中使用matDialogSpy检查单击按钮后对话框窗口是否打开：

it('should open dialog when button has been clicked', fakeAsync(() => {
clickOnSlsButtonByLabel('Open dialog', fixture);

expect(matDialogSpy.open).toHaveBeenCalledTimes(1);
expect(matDialogSpy.open).toHaveBeenCalledWith(
  PollComponent,
  {
    width: '400px',
    height: '400px',
    data: data...
  }
);

}））;