meta-updater
                                
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                        @pnpm/meta-updater
Keeps meta files up-to-date in a monorepo
Installation
<pnpm|yarn|npm> add @pnpm/meta-updater
Usage
Create a JavaScript file at .meta-updater/main.mjs that contains the updater functions.
Example 1
The following .meta-updater/main.mjs defines updaters for package.json and tsconfig.json files:
export default (workspaceDir) => {
  return {
    'package.json': (manifest, dir) => {
      return {
        ...manifest,
        author: 'Foo Bar',
      }
    },
    'tsconfig.json': (tsConfig, dir) => {
      return {
        ...tsConfig,
        compilerOptions: {
          outDir: 'lib',
          rootDir: 'src',
        },
      }
    },
  }
}
Example 2
The following .meta-updater/main.mjs defines format #ignore and updaters for .gitignore and .eslintrc using explicit format specifier.
import * as fs from 'fs/promises'
import { createFormat, createUpdateOptions } from '@pnpm/meta-updater'
/* default .eslintrc */
export const eslintrc = {}
/* default tsconfig.json */
export const tsconfig = { compilerOptions: { target: 'esnext' } }
/**
 * User-defined format '#ignore'
 */
const ignoreFormat = createFormat({
  async read({ resolvedPath }) {
    return (await fs.readFile(resolvedPath, 'utf8')).split('\n')
  },
  update(actual, updater, options) {
    return updater(actual, options)
  },
  equal(expected, actual) {
    return R.equals(expected, actual)
  },
  async write(expected, { resolvedPath }) {
    const unique = (array) => Array.from(new Set() < T[number] > array).sort()
    await fs.writeFile(resolvedPath, unique(expected).join('\n'), 'utf8')
  },
})
export default async (_workspaceDir) => {
  return createUpdateOptions({
    files: {
      // builtin
      'tsconfig.json': (actual, _options) => actual ?? tsconfig,
      // buildin .json format with explicit format specifier
      '.eslintrc [.json]': (actual) => actual ?? eslintrc,
      // user-defined `#ignore` format
      '.prettierignore [#ignore]': (actual) => actual ?? ['node_modules'],
    },
    formats: {
      '#ignore': ignoreFormat,
    },
  })
}
See more examples at src/examples/
To perform the update on the affected config files, run pnpm meta-updater.
To check that all meta files are up-to-date, run pnpm meta-updater --test. It is recommended to always check the meta files before running the tests, so add it to your test command:
{
  "test": "meta-updater --test && jest"
}
API
Updater Function: (config | null, dir, manifest) => Promise<config | null>
The updater function recieves the config object or null (if the config file does not exist). The updater function returns the config object that should be saved. If the updater function returns null, the config should be removed.
License
MIT © Zoltan Kochan