Support `@jest/globals`

[SimenB]

See jestjs/jest#9801.

We need to support finding expect, test, it etc when imported from @jest/globals. Should be relatively simple for ESM syntax, possibly a bit more pain for require. We need to support aliasing as well import { test as testFunction } from '@jest/globals'

Note that the feature hasn't been released yet (blocked by jestjs/jest#9806), but we can add support before it lands.

/cc @G-Rath

[G-Rath]

Hmmm this should mainly be a matter of inverting scopeHasLocalReference to test if a reference is an import from @jest/globals.

I'll have a toy around sometime over the weekend.

In saying that...

On the one hand arguably we don't have to do much to support them because as long as the globals are around (and doubly so if they're the default) then we always have to assume what could be the globals are the globals (aka what we do now).

On the other hand we could have the rules check if the env or globals are specified in the config Nope, near as I can tell eslint doesn't provide us a way to check what envs are enabled, nor what globals (because why would that ever be useful right? 🙄). In fact globals work inversely: if they're in globals they're not included in the global scope.

So we'd have to have a plugin setting for configuring if the global export is used 🤷

[SimenB]

I think we should check for the globals regardless - if the user don't want the globals to be used they should remove the global config. Only reason for introducing a plugin config would be for perf optimization - skipping searching the scope for the global. I doubt that'd make a big difference, though.

But yeah, in theory this should "just" be tweaking scopeHasLocalReference and seeing where what's referenced comes from

[G-Rath]

I think we should check for the globals regardless... Only reason for introducing a plugin config would be for perf optimization

I don't get what you mean - the problem is that we can't check if globals have been configured from within rules, so we have no way to magically detect if the user is wanting to use @jest/globals or not; hence we need a setting property either way.

i.e we figure out that expect is a global - then we need to know if export is defined as "our" jest global, or if we should be looking for @jest/globals.

I guess maybe we might be able to the globalScope.through to see if the identifier we've found is missing but I don't know how reliable that is :/

---

actually a better way of framing it:

if the user don't want the globals to be used they should remove the global config

We can't detect that, as we don't have access to the global config at lint-time from within the rules.

We only get passed the settings property.

[SimenB]

We shouldn't care what globals are configured for ESLint, we should always search for the globals Jest puts into the environment regardless of what ESLint considers as globals.

[G-Rath]

Oh are you saying that we should implementing that behaviour, "and also btw" we'll need amend it to support when importing from @types/jest as that will break our "is it a global" checks?

[SimenB]

Yup! I think that's reasonable

[SimenB]

This has shipped in 25.5. Messaging in https://github.com/jest-community/eslint-plugin-jest/blob/master/docs/rules/no-jest-import.md should probably account for this new package

[G-Rath]

Apologies I havn't had the time to do much on this, but agree updating that documentation would be a good first step.

[SimenB]

Nothing to apologize for! That's just the way of FOSS 🙂

[tettoffensive]

I'm not sure if this is related, (if not, i can start a new issue) but I'm finding that eslint isn't finding the globals defined in my setupFiles

./test/setup.js

import Enzyme, { configure, shallow, mount, render } from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';

configure({ adapter: new Adapter() });

// Make Enzyme functions available in all test files without importing
global.shallow = shallow;
global.render = render;
global.mount = mount;

export { shallow, mount, render };
export default Enzyme;

But when I try to use shallow in a test file:

Cannot find name 'shallow'.ts(2304)
'shallow' is not defined. eslint(no-undef)

I've tried the following with no change:

env: {
      "jest/globals": true,
    },

Is there some setting to configure this?

[G-Rath]

shallow isn't a Jest global :)

You can tell ESLint about additional globals using the globals property.

[SimenB]

When this lands we should also have some way of not sticking jest/globals into the recommended config:

eslint-plugin-jest/src/index.ts

Line 57 in d16b84c

env: { 'jest/globals': true },