Missing type definitions for expect imported from @jest/globals

[arty-name]

• @testing-library/jest-dom version: 5.16.1
• node version: v16.13.1
• yarn version: 1.22.17

Relevant code or config:

import { expect } from '@jest/globals';
import '@testing-library/jest-dom';
expect(container).toHaveAttribute('hidden');

What you did:

I imported jest globals from '@jest/globals'

What happened:

I got the TypeScript error message: TS2339: Property 'toHaveAttribute' does not exist on type 'Matchers '.

Reproduction:

import { expect } from '@jest/globals';
import '@testing-library/jest-dom';
expect(container).toHaveAttribute('hidden');

Problem description:

The custom matchers provided by jest-dom cannot be used in TypeScript if the expect is imported from @jest/globals. Only the global expect is modified, apparently.

Suggested solution:

Extend the interface of expect in the @jest/globals as well.

[gnapse]

Thanks for reporting this.

I have to say, I see this more as a problem with jest than with jest-dom, if really the solution involves duplicating the code that extends the interface of expect's return type. I hope there would a better solution where you extend it once, and no matter where you get expect from, it should work.

[arty-name]

After a deeper look, I see that the types of jest-dom extend jest.Matchers

Meanwhile, the types of @jest/globals simply re-export the type of the expect package

I’d naively expect that it’s rather expect.Matchers that should be extended, but after some poking around, I feel that I am out of my depth here.

[IanVS]

I'm importing expect directly from the expect package, and also struggling to get types working, since the way that jest-dom extends the types is by modifying the jest module, it seems. But I don't have that, since I'm using expect outside of jest. :(

[muratx10]

In my case, I've just switched to expect that comes from jest, not from jest/globals and it works like a charm.

[JoSuzuki]

I wasn't able to solve it the proper way either, but I've made a patch on the types coming from @jest/globals, in a declarations.d.ts file at the root of my project I've added the following configuration:

import type { TestingLibraryMatchers } from '@types/testing-library__jest-dom/matchers';
// import type { expect } from '@jest/globals'; <-- this was necessary because of my specific setup of cypress + jest, otherwise it was inferring the wrong expect

declare module '@jest/globals/node_modules/expect/build/types' {
  // eslint-disable-next-line @typescript-eslint/no-unused-vars, @typescript-eslint/ban-types
  export interface Matchers<R = void, T = {}>
    extends TestingLibraryMatchers<typeof expect.stringContaining, R> {}
}

this feels a bit risky because it relies on a path that could change at any moment (@jest/globals/node_modules/expect/build/types), but it was the best solution I could find for now.

[rtruong]

Is there a solution for this yet?

[aalpgiray]

I assumed this should worked but couldn't get it to work yet.

import matchers from '@testing-library/jest-dom/matchers';
import { expect } from '@jest/globals';

expect.extend(matchers);

[arty-name]

Looks like Jest@28 should enable that

[yordis]

I added the following to my globals.d.ts file

import type { TestingLibraryMatchers } from '@types/testing-library__jest-dom/matchers';

declare module '@jest/expect' {
  export interface Matchers<R = void, T = {}> extends TestingLibraryMatchers<typeof expect.stringContaining, R> {}
}

@jest/globals exports from @jest/expect the expect function

import type { JestExpect } from '@jest/expect';
export declare const expect: JestExpect;

[mrazauskas]

Just to add: since Jest v28 the above should work equally with declare module 'expect' or declare module '@jest/expect'.

By the way, it might be a good idea to include this augmentation declaration in @types/testing-library__jest-dom. So that matchers would have correct types for those who import { expect } form '@jest/globals'.

[Vinnl]

I submitted a PR to DefinitelyTyped that I think should fix this issue: DefinitelyTyped/DefinitelyTyped#65981