.each is unusable with @jest/globals

[danielmoore]

🐛 Bug Report

The return type of test.each is void | ((title: string, test: EachTestFn<TestFn>, timeout?: number | undefined) => void).

It should not include void, as this makes the result uncallable.

To Reproduce

With Jest v26.4.2 and Typescript v4.0.2, create each.test.ts.

import { expect, test } from '@jest/globals';

const items = test.each([['foo'], ['bar']]);

items('Test %s', item => {
  expect(item).toHaveProperty('length', 3);
});

test.each`
item
foo
bar
`(item => {
  expect(item).toHaveProperty('length', 3);
});

Steps to reproduce the behavior:

tsc produces:

each.test.ts:5:1 - error TS2349: This expression is not callable.
  Not all constituents of type 'void | ((title: string, test: EachTestFn<TestFn>, timeout?: number | undefined) => void)' are callable.
    Type 'void' has no call signatures.

5 items('Test %s', item => {
  ~~~~~

each.test.ts:9:1 - error TS2349: This expression is not callable.
  Not all constituents of type 'void | ((title: string, test: EachTestFn<TestFn>, timeout?: number | undefined) => void)' are callable.
    Type 'void' has no call signatures.

  9 test.each`
    ~~~~~~~~~~
 10   item
    ~~~~~~
...
 12 bar
    ~~~
 13 `(item => {
    ~


Found 2 errors.

Expected behavior

The given tests should compile.

envinfo

  System:
    OS: macOS 10.15.6
    CPU: (8) x64 Intel(R) Core(TM) i5-8279U CPU @ 2.40GHz
  Binaries:
    Node: 14.8.0 - /usr/local/bin/node
    Yarn: 1.22.4 - /usr/local/bin/yarn
    npm: 6.14.7 - /usr/local/bin/npm
  npmPackages:
    jest: ^26.4.2 => 26.4.2

[scttcper]

Running into the same thing, seems to have been changed in #9326

[SimenB]

Help with improving types is very much welcome 👍 Source is here: https://github.com/SimenB/jest/blob/c5785b9a71cc2edd8091cf67eae000c76010315c/packages/jest-types/src/Global.ts#L39-L48

We've recently landed the beginning of types tests to avoid these sorts of things, but it's not very comprehensive yet

[github-actions]

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