A script for "yarnifying" projects - updating them to use Yarn instead of npm.

yarnification.js

const chalk = require('chalk');
const fs = require('fs');
const del = require('del');
const spawnSync = require('child_process').spawnSync;


/**
 * A script for "yarnifying" projects - updating them to use Yarn instead of npm.
 * 
 * Usage:
 * `yarn` to install dependencies.
 * `cd` into the directory containing the project to be yarnified.
 * Run this script (no arguments necessary).
 *
 * If you plan to use this script many times, you might find it helpful to create a shell alias for it.
 */

console.log(chalk.magenta('\nyarnify.js...\n'));

// Git setup.
console.log(chalk.blue('\nGit setup...'));
console.log(chalk.blue('Checking out master'));
spawnSync('git', ['checkout', 'master'], {
  // Write to this process's stdout.
  stdio: 'inherit'
});

console.log(chalk.blue('Pulling the latest changes'));
spawnSync('git', ['pull'], {
  stdio: 'inherit'
});

// If you already have a "yarnify" branch, this will replace it.
console.log(chalk.blue('Checking out "yarnify" with `-B`'));
spawnSync('git', ['checkout', '-B', 'yarnify'], {
  stdio: 'inherit'
});

// Remove shrinkwrapping.
const shrinkwrapPath = `${process.cwd()}/npm-shrinkwrap.json`;
if (fs.existsSync(shrinkwrapPath)) {
  // Remove npm-shrinkwrap.json
  console.log(chalk.blue('\nRemoving `npm-shrinkwrap.json`.'));

  del.sync(shrinkwrapPath);

  if (fs.existsSync(shrinkwrapPath)) {
    console.log(chalk.red('Failed to delete `npm-shrinkwrap.json`'));
    process.exit(1);
  }

  console.log(chalk.blue('Removed `npm-shrinkwrap.json`.'));

  // Uninstall shrinkwrap packages.
  console.log(chalk.blue('\nUninstalling shrinkwrap dependencies.'));
  spawnSync('npm', ['uninstall', '--save-dev', 'npm-shrinkwrap'], {
    stdio: 'inherit'
  });
  spawnSync('npm', ['uninstall', '--save-dev', 'npm-shrinkwrap-check'], {
    stdio: 'inherit'
  });
}

// Remove node_modules if they exist in order to avoid any potential installation conflicts.
const nodeModsPath = `${process.cwd()}/node_modules`;
if (fs.existsSync(nodeModsPath)) {
  console.log(chalk.blue('\nRemoving `node_modules`.'));

  del.sync(nodeModsPath);

  if (fs.existsSync(nodeModsPath)) {
    console.log(chalk.red('Failed to delete `node_modules`'));
    process.exit(1);
  }

  console.log(chalk.blue('Removed `node_modules`.'));
}

// Run `yarn`.
console.log(chalk.blue('\nInstalling dependencies with yarn; generating `yarn.lock`.'));
spawnSync('yarn', [] /* empty args */, {
  stdio: 'inherit'
});

// Run `yarn check`.
console.log(chalk.blue('\n`check`ing that your dependencies installed correctly.'));
const checkStatus = spawnSync('yarn', ['check'], {
  stdio: 'inherit'
});

// Run tests.
console.log(chalk.blue('\nRunning `yarn test`.'));
spawnSync('yarn', ['test'], {
  stdio: 'inherit'
});

// Stage changes.
console.log(chalk.blue('\nStaging changes.'));
spawnSync('git', ['add', '.'], {
  stdio: 'inherit'
});
spawnSync('git', ['status'], {
  stdio: 'inherit'
});

// Output success.

// Prepare package.json `scripts` property for output.
const packageJsonPath = `${process.cwd()}/package.json`;
const packageJsonFile = fs.readFileSync(packageJsonPath, {
  encoding: 'utf8'
});
const packageJsonJson = JSON.parse(packageJsonFile);
const scripts = packageJsonJson.scripts;

console.log(chalk.green('\n\nSuccess!\n'));
console.log('NEXT STEPS:');
console.log('  1. Update package.json scripts if necessary:');
console.log('    ', chalk.cyan(JSON.stringify(scripts)));
console.log('  2. Update the README if necessary.');
console.log('    - Add preferred Yarn-install instruction');
console.log('    - Update any other npm commands to use Yarn instead');
console.log('  3. Update your CI configuration, if necessary');
console.log('  4. Perform any additional testing');
console.log('  5. Commit the changes made.');