Is it possible to have a version not depending on jest, @jest/globals ?

[ddolcimascolo]

Describe the feature you'd like:

A version of this package that does not have jest / @jest/globals as peer dependencies. These dependencies are installed automatically by npm (in recent versions) and if you're using Vitest and not Jest, you still end up installing tons of jest-related dependencies.

Any advice on how this could get implemented? I'm willing to help btw :)

Suggested implementation:

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy:

[gnapse]

Any advice on how this could get implemented? I'm willing to help btw :)

That's what I was planning to ask you as I read the first paragraph 😅

I guess we could try to make jest only a dev dependency, and remove the automatic setup entry points. That is, the "how to use instructions" will no longer include the ability to simply import a module from this library. The instructions will always be around this way of using the library, documented in our README:

With another Jest-compatible expect

If you are using a different test runner that is compatible with Jest's expect interface, it might be possible to use it with this library:

import * as matchers from '@testing-library/jest-dom/matchers'
import {expect} from 'my-test-runner/expect' // <- change this import path to jest or vitest or whatever

expect.extend(matchers)

There's the issue of the name, but I think that's secondary. It can always be named jest-dom. Though confusing, but it can be made independent of jest.

This would have to be a breaking change, but if it works, we can do it.

[ddolcimascolo]

What do you think of splitting this package into N packages with

• A core package (something like expect-dom) holding all the matchers, and any other code not-related to integrating with a test runner
• A jest-dom package (that depends on the core package) whose sole responsibility is to perform the integration with Jest
• A vitest-dom package (that depends on the core package) whose sole responsibility is to perform the integration with Vitest

This can scale if more test runners get supported in the future

The breaking change will only be for Vitest users (going from jest-dom to vitest-dom). Upgrade for Jest users will be transparent

[gnapse]

Yes, that could work too. But it complicates things. It involves setting up a mono-repo. I can help with reviewing and releasing, but not with implementing it.

Also, it's a change big enough (in terms of its implications) that it warrants asking the opinion of @testing-library/core-maintainers.

[kentcdodds]

I've been using @jest-dom with vitest without issue. I'm not sure what the problem is...

[kentcdodds]

Oh, just noticed the peerDeps. Yeah, I'd say just remove that and move on 🤷‍♂️

[kentcdodds]

Though, they're all marked as optional so it's really not a big deal IMO.

[kentcdodds]

These dependencies are installed automatically by npm (in recent versions) and if you're using Vitest and not Jest, you still end up installing tons of jest-related dependencies.

In my experience this is not true. For example, in the epic stack:

npm ls @jest/globals
epic-stack-template@ /Users/kentcdodds/code/epicweb-dev/epic-stack
└── (empty)

The only package in that project from @jest is @jest/schemas and that's coming from vitest:

npm ls @jest/schemas
epic-stack-template@ /Users/kentcdodds/code/epicweb-dev/epic-stack
└─┬ vitest@1.6.0
  ├─┬ @vitest/snapshot@1.6.0
  │ └─┬ pretty-format@29.7.0
  │   └── @jest/schemas@29.6.3
  └─┬ @vitest/utils@1.6.0
    └─┬ pretty-format@29.7.0
      └── @jest/schemas@29.6.3 deduped

I'm pretty sure this is not an issue.

[ddolcimascolo]

Thanks for checking Kent, let me double check why I have these installed then. My npm ls clearly states that they come from jest-dom but the setup in my project being a bit complex (I'm thinking npm workspaces for instance) I might have something else along the way.

David

[ddolcimascolo]

Ah @kentcdodds, the epic stack project uses the legacy-peer-deps npm option :) it's in .npmrc

For the record: https://docs.npmjs.com/cli/v10/using-npm/config#legacy-peer-deps

[kentcdodds]

Oh yeah, this is because the new peer deps behavior is stupid. And I guess this is one more reason to disable it 🤷‍♂️

[kentcdodds]

Anyway, not everyone's gonna want to disable it so I guess just remove the peerDeps and move on. Much better than complicating things with a ton of packages

[ddolcimascolo]

Great. Do you want me to open a PR for that?

[ddolcimascolo]

Done https://github.com/testing-library/jest-dom/pull/610

[ardeois]

This PR seems to have broken jest-dom when using pnpm

PNPM by default will not hoist packages to the top level node_modules, which means if jest-dom imports vitest it will fail unless:

• jest-dom packages declares vitest as peer dependency
• We override peerDependencies for jest-dom package in our project's package using pnpm.packageExtensions option

Having vitest declared as an optional peer dependency was I think the best option, I'm not sure to understand why this was removed?