jest-util pollutes types with own version of @types/node

[peterjuras]

🐛 Bug Report

As part of the migration to typescript, jest-util now has a dependency on @types/node.

This creates issues with code that will be written in a consuming TypeScript application, since some function types are modified (e.g. setTimeout). You can see more comments on similar issues here: https://github.com/DefinitelyTyped/DefinitelyTyped/issues/21310

I propose to remove the @types/node dependency from the jest-util package, in order to not affect any code that is written by the user.

[SimenB]

I was afraid something like this would be an issue. It's really unfortunate that TS allows the global namespace to be polluted by dependencies of dependencies

I propose to remove the @types/node dependency from the jest-util package, in order to not affect any code that is written by the user.

Then jest-util will not be consumable in TS since it will reference types that do not exist. How does other packages resolve this?

[peterjuras]

How about having the types as a peer or optional dependency

[dubzzz]

@SimenB Isn't the @types/node supposed to be in devDependencies? Not 100% sure but I believe it will be OK as soon as the packaged version of the jest-util package is the transpiled one

[milesj]

If Jest's public API (the compiled declaration files) rely on @types/node, then it must be a dependency, otherwise it can be a dev dependency. Otherwise, this forces the consumer to install @types/node manually, which non-TS users shoudn't have to do.

[dubzzz]

I believe that, in the case where jest-util uses types from the @types in its d.ts, going for peerDependencies or opt ones might be the right thing to do. In a way, types are only needed for TS users and are not really runtime constraints but just dev contraints.

EDIT

RXJS choice is to put it inside devDependencies:
https://github.com/ReactiveX/rxjs/blob/master/package.json

If you use rxjs with TypeScript you need to manually add @types/node to your package.json otherwise you will get error stacks as soon as you import it from a TypeScript file.

[SimenB]

Yeah, I think we'll do that as well. Sindre Sorhus does the same thing when adding typings now. The error TSC throws is pretty clear. Anybody wanna send a PR? We can just add @types/node to the root package.json and remove it from the individual packages.

Note that this is _just_ @types/node, all other @types/* should remain

[peterjuras]

Hi @SimenB,

out of curiosity, can you clarify which approach you would like to take? dubzzz's proposal?

[SimenB]

@types/node should only be in the package.json in the root of the repo, nowhere else

[dubzzz]

Do you mean in devDependencies? Like rxjs does.

[SimenB]

The root package.json is private, so it doesn't matter if it's dev or not. It's never published

[peterjuras]

Is there a plan to publish a new jest version which includes this change?

[SimenB]

There'll be a release next week

[SimenB]

https://github.com/facebook/jest/releases/tag/v24.6.0