feat: add `@jest/globals` package for importing globals explicitly #9801

SimenB · 2020-04-12T10:01:33Z

Summary

People have asked for it, so why not. We still add to the global env - we can remove that later if we want to (via some config flag I guess). If we want to do that it should be pretty straight forward, just add a runtime.registerGlobals function or some such and get the globals from that rather than environment.global. I don't want it to be import {test} from 'jest' as that's difficult to type correctly - a separate package can both ensure types are correct and that it's only used in a Jest environment.

Fixes #4473
Fixes #5192
Closes #7571
Closes #9306

Test plan

Integration test added

SimenB · 2020-04-12T10:02:24Z

packages/jest-globals/src/index.ts

+export declare type xdescribe = Global.GlobalAdditions['xdescribe'];
+export declare type fdescribe = Global.GlobalAdditions['fdescribe'];
+
+throw new Error(


this file ensure types are correct, but also that it's not imported outside of jest. Compiled code is just the throw

SimenB · 2020-04-12T10:03:18Z

packages/jest-circus/src/legacy-code-todo-rewrite/jestAdapter.ts

@@ -12,7 +12,8 @@ import type {TestResult} from '@jest/test-result';
 import type {RuntimeType as Runtime} from 'jest-runtime';
 import type {SnapshotStateType} from 'jest-snapshot';

-const FRAMEWORK_INITIALIZER = require.resolve('./jestAdapterInit');
+const FRAMEWORK_INITIALIZER = path.resolve(__dirname, './jestAdapterInit');
+const EXPECT_INITIALIZER = path.resolve(__dirname, './jestExpect.js');


changes not related, just some local cleanup from looking into not adding the globals to the global env. Went with a simpler solution, but I liked these refactorings 🤷

SimenB · 2020-04-12T10:03:33Z

scripts/buildTs.js

@@ -23,6 +23,24 @@ const packagesWithTs = packages.filter(p =>
  fs.existsSync(path.resolve(p, 'tsconfig.json'))
 );

+packagesWithTs.forEach(pkgDir => {


moved to verify before compiling

jeysal

Nice workaround, although I kinda wish for a better world now where we inject things into people's test fns, and global APIs are accessed via gimmeSomeThing(__filename) etc. 😄

jeysal · 2020-04-12T14:41:09Z

packages/jest-types/src/Circus.ts

@@ -16,7 +16,9 @@ export type BlockMode = void | 'skip' | 'only' | 'todo';
 export type TestMode = BlockMode;
 export type TestName = Global.TestName;
 export type TestFn = Global.TestFn;
-export type HookFn = (done?: DoneFn) => Promise<any> | null | undefined;
+export type HookFn = (


wWhy the asymmetry? Promise<unknown> and null instead of Promise<any> like in Global.TestFn, Global.HookFn, and Circus.TestFn

this was mostly me fixing a type error since it didn't accept void. Good point on the mismatch though - I'll push up exporting HookFn from Globals and reuse that here.

The type should ideally be Promise<void> | void, but then we don't get type errors if you return anything else. From my testing, void only matters to the caller, the callee doesn't have to fulfill that contract, it's just that the returned value cannot be used

Hmm, looks like it does matter https://www.typescriptlang.org/play?#code/MYewdgzgLgBAHgLhgNxASwCYwLwwCwBMA3AFABmArmMFGuDGQBQCUSqmMA3iTLzAE4BTKBX5h8xEgF8gA

Oh, nice! Can change then 👍 Should probably keep Promise<unknown> just so people can do test('t', () => promiseThing())

Actually, nevermind, this might be the problem https://www.typescriptlang.org/play?#code/MYewdgzgLgBAZgLhgCgJQwLwD4YDcQCWAJpiutjACwBMA3EA

ah, there you go! Adding |undefined makes it behave like we want, though

jeysal · 2020-04-12T14:42:22Z

scripts/buildTs.js

+    throw new Error(`Package ${pkg.name} is missing \`types\` field`);
+  }
+
+  if (!pkg.typesVersions) {


Should this also check the content? Just to make sure they are all the same since they do all use the same downleveling build process.

meh 😀 This is more "did you really mess up" than any thorough check

SimenB · 2020-04-12T15:01:52Z

Nice workaround, although I kinda wish for a better world now where we inject things into people's test fns, and global APIs are accessed via

100% agreed, this is a first step 😀

SimenB · 2020-04-12T15:11:14Z

packages/jest-types/src/Circus.ts

@@ -16,7 +16,7 @@ export type BlockMode = void | 'skip' | 'only' | 'todo';
 export type TestMode = BlockMode;
 export type TestName = Global.TestName;
 export type TestFn = Global.TestFn;
-export type HookFn = (done?: DoneFn) => Promise<any> | null | undefined;


we don't actually accept null, we check for void 0 which is an non-strict mode way of saying undefined

FezVrasta · 2020-04-12T19:10:49Z

Is it now possible to use Jest with Flow without having to install the flow-types definitions?

SimenB · 2020-04-12T19:13:24Z

No, we don't ship Flow definitions, only TypeScript.

silverwind · 2020-04-12T23:56:06Z

Bit of a shame those are not exported from jest.

import/no-extraneous-dependencies would force a @jest/globals dependency that may get incompatible with jest if not updated in tandem. Not sure I like this over just using the globals.

SimenB · 2020-04-13T00:30:40Z

They'll always get updated together, so shouldn't get out of sync in practice. We haven't changed our global API in years, so I doubt they'll drift anytime soon 🙂

SimenB · 2020-04-13T08:26:14Z

@silverwind main reason for not implementing it in the jest package is types - we already have code in jest and making that play nice with types is hacky I think.

https://github.com/facebook/jest/blob/c83051789cc60789f2c575374270236e3a428879/packages/jest/src/jest.ts

Those imports are pretty useless, so one thing we could do is make jest just be a re-export of the globals in Jest 26.

SimenB · 2020-04-13T10:29:46Z

One limitation I thought of now is that jest.mock calls where jest is imported from @jest/globals won't be hoisted, so mocking might silently not work... I'll give it a whack

jeysal · 2020-04-13T10:33:46Z

True, should be easy to fix in Babel plugin jest hoist though

SimenB · 2020-04-13T12:21:42Z

I tried (and failed) in #9806, help appreciated 🙂

SimenB · 2020-04-19T21:02:37Z

Need to make a release, so I'll be reverting this until we're able to fix the Babel plugin (#9806). Will hopefully be included in the next release!

…citly (#9801)" This reverts commit 2882d28.

…ls explicitly (jestjs#9801)"" This reverts commit 75ab1ab.

github-actions · 2021-05-11T09:06:39Z

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.
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SimenB requested review from thymikee and jeysal April 12, 2020 10:01

facebook-github-bot added the cla signed label Apr 12, 2020

SimenB commented Apr 12, 2020

View reviewed changes

feat: add @jest/globals package for importing globals explicitly

4bc98b5

SimenB force-pushed the import-globals branch from 2138478 to 4bc98b5 Compare April 12, 2020 10:04

SimenB added 2 commits April 12, 2020 13:58

add missing hooks

96cef21

use dedicated type for framework globals

3aef5f6

jeysal reviewed Apr 12, 2020

View reviewed changes

move HookFn type to Global, and correct signature

7b82687

SimenB commented Apr 12, 2020

View reviewed changes

SimenB added 2 commits April 12, 2020 17:38

no explicit undefined

bb5e1fe

bring back undefined

69302ac

SimenB merged commit 2882d28 into jestjs:master Apr 12, 2020

SimenB deleted the import-globals branch April 12, 2020 16:23

This was referenced Apr 12, 2020

Add ability to explicitly import global variables #4473

Closed

import jest functions instead of having globals #5192

Closed

Allow importing Jest as an ES6 module #7571

Closed

add noJestGlobals config, if false, no jest-circus globals #9306

Closed

SimenB mentioned this pull request Apr 15, 2020

Support @jest/globals jest-community/eslint-plugin-jest#556

Closed

SimenB added a commit that referenced this pull request Apr 19, 2020

Revert "feat: add @jest/globals package for importing globals expli…

75ab1ab

…citly (#9801)" This reverts commit 2882d28.

SimenB added a commit to SimenB/jest that referenced this pull request Apr 20, 2020

Revert "Revert "feat: add @jest/globals package for importing globa…

4ffd3fd

…ls explicitly (jestjs#9801)"" This reverts commit 75ab1ab.

SimenB mentioned this pull request Apr 20, 2020

feat: add @jest/globals package for importing globals explicitly #9849

Merged

This was referenced Apr 28, 2020

[WIP] Adds state and run exports to index #8748

Closed

fix(jest): use @jest/globals package DefinitelyTyped/DefinitelyTyped#44365

Draft

jdbruijn mentioned this pull request Sep 5, 2020

Add configuration to configure Jest test methods in global environment #10481

Closed

dependabot bot mentioned this pull request Mar 17, 2021

Bump jest from 25.3.0 to 25.5.4 newerton/gostack-template-fundamentos-node#10

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feat: add `@jest/globals` package for importing globals explicitly #9801

feat: add `@jest/globals` package for importing globals explicitly #9801

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feat: add @jest/globals package for importing globals explicitly #9801

feat: add @jest/globals package for importing globals explicitly #9801

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SimenB commented Apr 12, 2020 • edited Loading

Summary

Test plan

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feat: add `@jest/globals` package for importing globals explicitly #9801

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