[Bug]: Types no longer allow passing a named function to describe

[JoshuaKGoldberg]

Version

27.0.6 and 28.0.0-alpha.4

Steps to reproduce

https://www.typescriptlang.org/play?#code/JYWwDg9gTgLgBAbzgEwKYGcDGVgCNVwC+cAZlBCHAOQACAVhjAPQDmANhLgIZvpUDcAKEEkArgDtMMYBHFwQATwBiEqTLkAKAJSJCQwWiw58GxSsnTZAGjja4AXgB8urfyA

Expected behavior

No type errors on describe(myFunction, () => {})

Actual behavior

Argument of type '() => void' is not assignable to parameter of type 'string'.

Additional context

Allowing taking in class/function names in describe was added in #5154 and typed in @types/jest in DefinitelyTyped/DefinitelyTyped#23102.

Tests still pass while taking in a name; it's just the typings that are incorrect.

Environment

System:
    OS: Linux 5.10 Ubuntu 20.04.3 LTS (Focal Fossa)
    CPU: (8) x64 11th Gen Intel(R) Core(TM) i7-1185G7 @ 3.00GHz
  Binaries:
    Node: 16.13.0 - /usr/bin/node
    Yarn: 3.2.0 - /usr/local/bin/yarn
    npm: 8.1.0 - /usr/bin/npm
  npmPackages:
    jest: workspace:* => 28.0.0-alpha.4

[SimenB]

Ah, good catch!

/cc @mrazauskas

[mrazauskas]

Hm.. I was going through the discussion in the PR which added this feature. The maintainers seemed to be skeptical and the only convincing argument was legacy browsers #5154 (comment). Is this still an issue? IE is gone.

I have a feeling it might be equally good idea to deprecate this feature. Time comes and older Node version is not supported, the same about browsers.

https://github.com/facebook/jest/blob/c65bb4521597fb1ad65dacd778a26e04684b2872/packages/jest-util/src/convertDescriptorToString.ts#L11-L13

Instead one can easily have '123' (number), '' (undefined), 'true' (boolean, if you wish), someFunction.name (works too). So is this feature still relevant or is that just legacy code?

[SimenB]

I don't really see a reason to remove the feature - it's a nice shorthand, and runtime support is already present, it's only the types that don't recognize it

[JoshuaKGoldberg]

FWIW I agree with SimenB and think being able to to describe(myFunction) instead of describe(myFunction.name) is itself a nice feature. Keeping hardcoded strings like describe("myFunction") between refactorings is a pain.

[SimenB]

https://github.com/facebook/jest/releases/tag/v28.0.0-alpha.5

[github-actions]

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