Using `expect.any(Object)` or `expect.anything()` does not work to match `undefined` in Jest

Question

I have the following module which I want to test.

import * as apiUtils from './apiUtils';

export function awardPoints(pointsAwarding) {
  return apiUtils.callApiService("POST", "points", pointsAwarding);
}

And this is my test.

it("should call apiUtils with correct path", () => {
  //given
  jest.spyOn(apiUtils, 'callApiService');

  //when
  pointsAwardingApi.awardPoints();

  //then
  expect(apiUtils.callApiService).toBeCalledWith(expect.any(String), 'points', expect.any(Object));
});

When I try to run this test I get the following error.

Any<Object> as argument 3, but it was called with undefined.

I was expecting that expect.any(Object) would also match undefined but it seems that's not the case.

I also tried with expect.anything() but I get a similar error.

I could simply specify undefined as the third parameter but my test is only intended to verify the second parameter.

Is there a way I can use a matcher that matches any object including undefined?

Answer 1

It looks like expect.anything doesn't match unset values by design. If you need a "really anything" matcher, here's one:

export const expectAnythingOrNothing = expect.toBeOneOf([expect.anything(), undefined, null]);

You'll need jest-extended for the toBeOneOf matcher -- but it's a useful package anyway :)