Add eslintTask to just-scripts

[Thisen]

Since TypeScript itself are moving to ESLint, it would be a great addition to add aneslintTask() to just-scripts, similar to tslintTask().

[kenotron]

Yes yes yes! Would you want to actually write a task? @Thisen

[Thisen]

Sure thing, I can give it a shot @kenotron.

[Thisen]

@kenotron, I'm not sure how I can contribute with the Rush git policies of this repository. Anything I'm missing?

[Thisen]

My first iteration (not done) looks like this:

import { resolve, logger, resolveCwd, TaskFunction } from 'just-task';
import { exec, encodeArgs } from 'just-scripts-utils';
import fs from 'fs';

export interface EsLintTaskOptions {
  configPath?: string;
  ignorePath?: string;
  fix?: boolean;
}

export function eslintTask(options: EsLintTaskOptions = {}): TaskFunction {
  return function eslint() {
    const eslintCli = resolve('eslint/lib/cli.js');
    const eslintConfigPath = resolveCwd((options && options.configPath) || '.eslintrc.js');

    if (eslintCli && eslintConfigPath && fs.existsSync(eslintConfigPath)) {
      logger.info(`Running ESLint`);
      const eslintIgnorePath = resolveCwd((options && options.ignorePath) || '.eslintignore');

      const eslintArgs = [
        eslintCli,
        ...(eslintConfigPath ? ['--config', eslintConfigPath] : []),
        ...(eslintIgnorePath ? ['--ignore', eslintIgnorePath] : []),
        ...(options.fix ? ['--fix'] : [])
      ];

      const cmd = encodeArgs([process.execPath, eslintCli, ...eslintArgs]).join(' ');
      logger.info(cmd);
      return exec(cmd, { stdout: process.stdout, stderr: process.stderr });
    } else {
      return Promise.resolve();
    }
  };
}

It's on purpose that not every CLI options in ESLint are exposed, since I see that pattern in the other tasks.

Do you just to expose everything or you want something more strict?

Other than that, I chose to have .eslintrc.js as the default - Of course this can be changed aswell.

[Thisen]

Hi @kenotron,

I've finished a ESLint task, that I'm using in my current project. It's written in JS, since it's used by our just-scripts task directly, but it's easily migrated to TypeScript and more standardized:

function eslintTask(options) {
  return function eslint() {
    const eslintCmd = resolve("eslint/bin/eslint.js");
    const eslintConfigPath = (options && options.configPath) || resolveCwd(".eslintrc");
    if (eslintCmd && eslintConfigPath && fs.existsSync(eslintConfigPath)) {
      const eslintIgnorePath = (options && options.ignorePath) || resolveCwd(".eslintignore");

      const eslintArgs = [
        eslintCmd,
        ...(options && options.files ? options.files : ["."]),
        ...(eslintConfigPath ? ["--config", eslintConfigPath, "--no-eslintrc"] : []),
        ...[
          "--ignore-path",
          eslintIgnorePath ? eslintIgnorePath : path.resolve(__dirname, "..", "..", ".eslintignore")
        ],
        ...(options && options.fix ? ["--fix"] : []),
        ...["--max-warnings", "0"],
        "--color"
      ];

      logger.info(encodeArgs(eslintArgs).join(" "));
      return spawn(process.execPath, eslintArgs, { stdio: "inherit" });
    } else {
      return Promise.resolve();
    }
  };
}

Let me know what you think in terms of interface.

[kenotron]

@Thisen - I recently swapped to lerna + yarn. This should help! I don't have a "CONTRIBUTING.md" type thing up yet, but will now do so 👍

[kenotron]

Would you terribly mind to make a PR with this?