jest: [Bug]: `jest.mocked` function is not exported from `jest` object

Version

27.4.3

Steps to reproduce

Try to use jest.mocked. E. g.:

// foo.ts
export const foo = { };

// foo.spec.ts
import {foo} from './foo';
jest.mock('./foo');

const mockedFoo = jest.mocked(foo);

Expected behavior

jest.mocked is defined and working.

Actual behavior

Error: TypeError: jest.mocked is not a function.

Also documentation is missing on https://jestjs.io/docs/jest-object, but present in source code: https://github.com/facebook/jest/blob/main/docs/JestObjectAPI.md#jestmockedtitem-t-deep--false

Additional context

jest.mocked was added in https://github.com/facebook/jest/pull/12089, but seems it was not added to jest object, and only to jest-mock package.

Tagging author of original PR @k-rajat19

Environment

System:
    OS: macOS 11.6.1
    CPU: (8) x64 Intel(R) Core(TM) i5-1038NG7 CPU @ 2.00GHz
  Binaries:
    Node: 16.13.0 - /usr/local/bin/node
    Yarn: 1.22.17 - /usr/local/bin/yarn
    npm: 8.2.0 - /usr/local/bin/npm
  npmPackages:
    jest: ^27.4.3 => 27.4.3

About this issue

Original URL
State: closed
Created 3 years ago
Reactions: 6
Comments: 15 (8 by maintainers)

Most upvoted comments

You can use import { jest } from '@jest/globals'; (which is what you must use for native ESM anyways)

SimenB on Dec 15, 2021

domdomegg on Dec 15, 2021

Ah, missed adding it to jest object. We need to add to https://github.com/facebook/jest/blob/c76f9a7c8eb2fab1a15dfe8952d125a8607d1bbe/packages/jest-environment/src/index.ts#L51 at which point we’ll get a type error in jest-runtime which should lead the way

/cc @k-rajat19

SimenB on Dec 7, 2021

I’m getting an error: https://app.circleci.com/pipelines/github/ike18t/ng-mocks/2810/workflows/cad5fba3-e1c9-4e59-9d20-daf923c60c31/jobs/101406

    TypeError: Cannot read properties of undefined (reading 'bind')

      at Runtime._createJestObjectFor (node_modules/jest-runtime/build/index.js:2193:46)

is it possible that mocked isn’t present in some cases?

satanTime on Dec 25, 2021

I don’t know why you keep discussing this here - there is absolutely nothing to do in this repo. @types/jest comes from https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/jest/index.d.ts, jest.mocked just needs to be added there

SimenB on Dec 20, 2021

One thing I don’t understand though is how anyone can use the new mocked function without it being added to @types/jest? My understanding is that the function just returns the input object and all the magic/purpose happens in the typing. Thus I was querying if there’s some other way (other than @types/jest) we’re supposed to be getting jest types?

hey @cduff, So for the time being, what you can do is this, since the mocked function is already exported in jest-mock anyway.

import { mocked } from 'jest-mock';

these test helper are not depend on @types/jest for their types, all their types are defined in jest-mock.

@k-rajat19 I agree that it’s not dependent on @types/jest for their types, but it would be easier (DX-wise) to make it available in the @types/jest package, so the usage can be consistent in TS/JS usage, and also with what is described in the Docs (i.e. you shouldn’t need to import jest-mock for the mocked function to work in TS, while it can already work in JS). And then again, this is an issue for the @types/jest package in DefinitelyTyped, not here (like @SimenB said above) 😄

samhwang on Dec 17, 2021