useFaketimers not behaving as a spy function after updating to 27.0.0

[asthemus]

🐛 Bug Report

I updated my repository to use jest@27.0.0 and started to get error because of jest.setTimeout not behaving as a spy function anymore.

To Reproduce

created a simple project to demonstrate the issue

app.ts

import {timeoutFn} from './app'
describe('test func', () => {
	test("test timeoutFn", () => {
		jest.useFakeTimers()
		timeoutFn()
		expect(setTimeout).toBeCalled()
	})
})

app.test.js

export const timeoutFn = () => {
	console.log('the first statement')
	global.setTimeout(() => {
		console.log('the second statement')
	}, 1000)
}

Expected behavior

earlier the test should have passed perfectly without any issue but now I get the error

 ● test func › test timeoutFn

    expect(received).toBeCalled()

    Matcher error: received value must be a mock or spy function

    Received has type:  function
    Received has value: [Function setTimeout]

      18 |                      jest.useFakeTimers()
      19 |                      timeoutFn()
    > 20 |                      expect(setTimeout).toBeCalled()
         |                                         ^
      21 |              })
      22 | })

envinfo

envinfo

  System:
    OS: macOS 10.15.7
    CPU: (16) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
  Binaries:
    Node: 14.15.4 - /usr/local/bin/node
    Yarn: 1.22.10 - /usr/local/bin/yarn
    npm: 6.14.10 - /usr/local/bin/npm
  npmPackages:
    jest: ^27.0.0 => 27.0.4 

Edit:

just checked out release notes to see that with new jest release, it gives option to use jest.useFakeTimers('modern') and jest.useFakeTimers('legacy') even tho legacy works fine now but I face the same error mentioned above while using 'modern'

[Smrtnyk]

Thats intended
Check changelog for jest 27

You should spy on global.setTimeout and then assert the calls

[edmundask]

It's also worth pointing out that a spy should be set up after jest.useFakeTimers, as otherwise your expectations may not pass as intended.

it('calls setInterval', () => {
  jest.useFakeTimers()
  setIntervalSpy = jest.spyOn(global, 'setInterval')

  foobar()

  // Works as intended
  expect(setIntervalSpy).toHaveBeenCalled()
})

vs

it('calls setInterval', () => {
  setIntervalSpy = jest.spyOn(global, 'setInterval')
  jest.useFakeTimers()

  foobar()

  // Expected number of calls: >= 1
  // Received number of calls:    0
  expect(setIntervalSpy).toHaveBeenCalled()
})

[mikl]

I don’t see where the changelog mentions this change?

I came here from the Jest timers documentation that still has the old (now broken) code, just FYI.

[riderx]

Even with your code @edmundask i don't get all call like i should.
test Code :

export const timerGame = (callback: any) => {
  console.log('Ready....go!');
  setInterval(() => {
    console.log("Time's up -- stop!");
    callback && callback();
  }, 1000);
}

and the test

import { timerGame } from '../timer';
// test.ts
jest.useFakeTimers();

test('waits 1 second before ending the game', () => {
  const setIntervalSpy = jest.spyOn(global, 'setInterval')
  timerGame(() => {});
  expect(setIntervalSpy).toHaveBeenCalledTimes(0);
  jest.advanceTimersByTime(1000)
  expect(setIntervalSpy).toBeCalled();
  expect(setIntervalSpy).toHaveBeenLastCalledWith(expect.any(Function), 1000);
  expect(setIntervalSpy).toHaveBeenCalledTimes(1);
  jest.advanceTimersByTime(1000)
  jest.advanceTimersByTime(1000)
  expect(setIntervalSpy).toHaveBeenCalledTimes(3);
});

it's always call 1 time only

[SimenB]

I don’t see where the changelog mentions this change?

[jest-config, jest-runtime] [BREAKING] Use "modern" implementation as default for fake timers (https://github.com/facebook/jest/pull/10874 & https://github.com/facebook/jest/pull/11197)

I came here from the Jest timers documentation that still has the old (now broken) code, just FYI.

#11974

[github-actions]

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