你可以通过模拟getDataValues()函数的返回值来测试它。

describe('Service', () => {
  let service: Service;
  
TestBed.configureTestingModule({
  // imports, providers and declarations come here::
}).compileComponents();

beforeEach(() => {
  service = TestBed.inject(Service);
});

it('export', () => {
  const mockData = {
    // create an object with the same type as your expected returnData
  }
  jest.spyOn(service, 'getDataValues').mockReturnValue(of(mockData));
  jest.spyOn(service, 'exportDelays').mockImplementation();
  jest.spyOn(service, 'exportCancels').mockImplementation();

  service.export();
 
  expect(service.getDataValues).toHaveBeenCalled();
  expect(service.exportDelays).toHaveBeenCalled();
  expect(service.exportCancels).toHaveBeenCalled();
}

请注意，您需要返回一个可观察对象，它通过将of(mockData)作为returnValue传递来发出您的mockData。只有这样，该函数才能订阅并触发其他服务方法。