What is the reasoning behind remove-empty/import?

[EvgenyOrekhov]

Using "empty" imports for side effects is a fairly common practice:

// jest.setup.js
import "@testing-library/jest-dom/extend-expect.js";

What is the reasoning behind removing them by default?

[coderaiser]

Because it’s not common practice for built-ins, there is a lot ways to import module like fs or any module from the wild:

import ‘fs’;
import ‘mock-import’;

That has no sense. Also with help of ignore option any most used this way modules can be listed and excluded.

Do you have a list of such modules?

[EvgenyOrekhov]

Not sure about built-ins, but empty imports are used pretty often by 3rd-party libraries.

Thanks for clarifications, I decided to disable remove-empty/import (along with import/no-unassigned-import) in eslint-config-hardcore: https://github.com/EvgenyOrekhov/eslint-config-hardcore/releases/tag/v19.10.0.

[coderaiser]

I see that jest-dom suggest to use:

import '@testing-library/jest-dom'

Let's look what is inside src/extend-expect.js:

import * as extensions from './matchers'
expect.extend(extensions)

You can use similar approach and this is is more obvious to understand what is going on here without any documentation. supertape behave in a similar way:

const {extend} = require('supertape');
const test = extend({
    transform: (operator) => (a, b, message = 'should transform') => {
        const {is, output} = operator.equal(a + 1, b - 1);
        return {
            is,
            output,
        };
    },
});

test('assertion', (t) => {
    t.transform(1, 3);
    t.end();
});

With no pollution of global scope. Many task runners adds global variables but I don't think this is a good practice for example js-based Test Anything Protocol runners can work without separated utility you just execute your test with:

node test.js

And it just works as any other script, with jest, mocha etc you can't do such a trick.
Anyways jest is very good task runner with a lot of features, supertape is the complete oppositeЖ the realm of minimalism :).

Also worth mention that: Explicit is better than implicit according to Zen of Python. Also such a way is violates Principle of least astonishment: when you see empty import first thing you want to do is delete it (if it's not css in React Component of course).

[EvgenyOrekhov]

I agree that it would be better to avoid unassigned imports, but unfortunately many libraries recommend using unassigned imports in the official docs, and it just becomes annoying to see false-positive warnings from import/no-unassigned-import and remove-empty/import.