putout v24.3.0

ESLint API

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Zhuangzi

Hi foks! Let's talk about ESLint API a little bit more.

ESLint begins his work as a formatter when 🐊Putout done his transformations. That's why it used a lot in different parts of application, for testing purpose and using API in a simplest possible way. You can access it with:

import {eslint} from 'putout/eslint';

To use it simply write:

const [source, places] = await eslint({
    name: 'hello.js',
    code: `const t = 'hi'\n`,
    fix: false,
    config: {
        extends: [
            'plugin:putout/recommended',
        ],
    },
});

Isn't it looks similar to 🐊Putout way? It definitely is! But... It has a couple differences you should remember:

• ☝️ 🐊Putout returns object with code and places properties.
• ☝️ ESLint has a name property that is used to calculate configuration file.

If you want to apply 🐊Putout transformations using putout/putout ESLint rule, enable putout with the same called flag:

const [source, places] = await eslint({
    name: 'hello.js',
    code: `const t = 'hi'\n`,
    fix: true,
    putout: true,
    config: {
        extends: [
            'plugin:putout/recommended',
        ],
    },
});

It is disabled by default, because ESLint always runs after 🐊Putout transformations, so there is no need to traverse tree again.

What with 🎩ESCover?

🎩ESCover is ready to be used in a regular basis 🎉!
The only thing is: it works with EcmaScript Modules only. And this is for a reason: for CommonJS you can use c8 and nyc/istanbul. But there is no tool that shows coverage for files changed with node loaders.

What's inside of 🎩ESCover?

Inside of 🎩ESCover you can find the plugin for 🐊Putout which sets markers that should be called.
Results saved to coverage/lcov.info to read them when done.

-☝️ lcov was created in 2002, almost twenty years ago.
-☝️ Linux kernel developers created it to know what is going on with the coverage.
-☝️ It's written in PERL and has text based format.
-☝️ This is most popular coverage format of all times supported by a lot of tools (like coveralls).

So if we run our ESM application with:

estrace npm test

We will receive something similar to:

SF:/Users/coderaiser/escover/lib/transform.js
DA:1,1
DA:3,1
DA:7,1
DA:9,1
DA:10,1
DA:12,1
DA:24,1
DA:25,1
DA:27,1
DA:28,1
DA:29,1
DA:32,1
end_of_record

Where:

• SF - is path to source;
• DA - is line number, and count of running;
• end_of_record latest recored for current file entry;

As for me this is really human readable, and very compact form. The only thing I don't get for now is: counters, I see no reason why do I need them 🤷‍♂️, if you have a reason create an issue. It can be added in one line of code.

That's all for today!
Have a nice day 🏝!

🔥 feature

• (putout) eslint: add ability to enable putout/putout rule with a flag
• (putout/eslint) add ability to enable putout