do not modify global types via declarations

[cspotcode]

Summary

This is a fix for #8570.

Test plan

[SimenB]

we should not be messing with the global at all, could you just remove this entire declare global { block? And rollback the other changes in this PR. We might want/need some kind of JestGlobalEnv:

interface JestGlobal extends NodeJS.Global {
  // ...blahblahblah
}

but it should not mutate the actual global type environment

---

The TS types are mostly internal for now, they are not meant to replace @types/jest yet. When they are it'll be the jest package itself sticking things on global

[cspotcode]

I haven't used jest in a little while, but describe() is available globally, right? As in, users do not need to import it. If so it needs to be declared globally somewhere for users of Jest. But I don't know if you want that to be happening within @jest/types or somewhere else.

[cspotcode]

I missed your last sentence about omitting the global declarations for now and eventually moving them into the jest package. Roger that.

Is there any harm in me moving the globals to the jest package right away? If people are still using @types/jest, it'll be ignored. But if they skip that and use the types bundled in jest, it'll pick up the global declaration and everything will work.

Or should it always be opt-in to get the global declarations? E.g. people can import 'jest'; without the global declarations, and they'll need to explicitly /// <reference types="jest/globals" /> to get the global types? Will anyone ever want to import jest from 'jest'; to use the API, without getting the global declarations?

[SimenB]

For now, the way to get the global type defs with Jest should be @types/jest. THat will change at some point, but for now we do not support patching the global types

[cspotcode]

@SimenB Have you hit issues where the Typescript compiler uses node_modules/jest types, skipping node_modules/@types/jest? That's the behavior I'm seeing. It doesn't matter if the user installs a @types package. It'll be ignored if the non-@types package bundles its own declarations.
https://repl.it/@AndrewBradley/SpanishHugeVirus-1

[SimenB]

no, but you can use

{
  "compilerOptions": {
    "paths": {
      "jest": ["./node_modules/@types/jest", "./node_modules/jest"]
    }
  }
}

or something like that to prioritize DT's typings

[codecov-io]

Codecov Report

Merging #8571 into master will decrease coverage by <.01%.
The diff coverage is 10%.

@@            Coverage Diff             @@
##           master    #8571      +/-   ##
==========================================
- Coverage    63.2%   63.19%   -0.01%     
==========================================
  Files         271      271              
  Lines       11284    11285       +1     
  Branches     2749     2749              
==========================================
  Hits         7132     7132              
- Misses       3538     3539       +1     
  Partials      614      614

Impacted Files	Coverage Δ
packages/jest-jasmine2/src/setup_jest_globals.ts	0% <ø> (ø)	⬆️
packages/jest-jasmine2/src/jestExpect.ts	0% <ø> (ø)	⬆️
...us/src/legacy-code-todo-rewrite/jestAdapterInit.ts	0% <0%> (ø)	⬆️
packages/jest-each/src/index.ts	100% <100%> (ø)	⬆️

---

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[cspotcode]

Another question: I see that a bunch of the jest type declarations refer to NodeJS types but don't declare a "@types/node": "*" dependency.

Do you want to add that dependency to those modules or instead stub out the global NodeJS namespace with empty interfaces?

[SimenB]

Another question: I see that a bunch of the jest type declarations refer to NodeJS types but don't declare a "@types/node": "*" dependency.

Do you want to add that dependency to those modules or instead stub out the global NodeJS namespace with empty interfaces?

That's on purpose due to #8092

[cspotcode]

As far as I know this is good to go. Is there anything else that needs to be added?

[SimenB]

Thanks!

[matthoang08]

Hi, I found this PR referenced here https://stackoverflow.com/questions/56181799/how-to-use-mocha-and-jest-with-typescript-without-conflicts

Is there any reason why this wasn't released? Or is it released already? I am trying to use Mocha for integration test and jest for unit tests and I'm running into this issue.

Thanks!

[SimenB]

This was released in 24.9.0 last week

[github-actions]

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