New Cypress 10 global TypeScript type conflicts with Jest `expect`

Current behavior

The following new global TypeScript type for expect in node_modules/cypress/types/cypress-expect.d.ts causes conflicts with Jest expect types, if a project has both Jest and Cypress:

https://github.com/cypress-io/cypress/blob/a0a64cc851c8232b94eb0e907f220e08260bda20/cli/types/cypress-expect.d.ts#L2

Errors:

Property 'toBe' does not exist on type 'Assertion'.

When looking through the docs, there is a guide here:

Cypress Types Conflict with Jest

However, this guide is based on the fact that Cypress types were not global before (but they are now).

Desired behavior

No response

Test code to reproduce

Jest test code (filename __tests__/colors.test.ts):

import { findWhiteContrastingColor } from '../colors';

test('findWhiteContrastingColor finds colors contrasting with white', () => {
  expect(findWhiteContrastingColor(['#ffffff', '#000000', '#e1e1e1'])).toBe(
    '#000000',
  );
});

Cypress Version

10.0.1

Other

No response

[ZachJW34]

@karlhorky thanks for posting, looks like you’re not the only one having issues with Cypress + Jest type collisions.

I was able to reproduce this with the repos linked @karlhorky @mrdrogdrog @wKovacs64. When I checked out the dep update to v10, all of the Jest tests started complaining.

We didn’t change our globals very much for v10. For all the cases I reproduced, it was fixed by adding ./cypress.config.ts to the tsconfig.exclude property. Since the cypress.config.ts is being included in the type checking, it is loading the cypress types which is polluting your jest tests.

[gustavodamazio]

./tsconfig.json, include types and exclude properties in config file.

{
  "compilerOptions": {
    ...
    "types": ["jest", "node", "@types/testing-library__jest-dom"]
  },
  "exclude": ["node_modules", "cypress", "./cypress.config.ts"]
}

cypress/tsconfig.json

{
  "extends": "../tsconfig.json",
  "compilerOptions": {
    "noEmit": true,
    "types": ["cypress"]
  },
  "exclude": ["node_modules"]
}