feat(config): add support for loading configs from npm itself

lib/config.js

@@ -1,17 +1,56 @@
 'use strict'
 
 const figgyPudding = require('figgy-pudding')
+const spawn = require('child_process').spawn
 
-module.exports = figgyPudding({
+const frogConfig = module.exports = figgyPudding({
  also: {},
  cache: {},
  dev: {},
  development: {},
  force: {},
+ global: {},
  'ignore-scripts': {},
  log: {},
+ loglevel: {},
  only: {},
  prefix: {},
  production: {},
+ then: {}, // omfg
  umask: {}
 })
+
+module.exports.fromNpm = getNpmConfig
+async function getNpmConfig (argv) {
+ const npmBin = process.platform === 'win32' ? 'npm.cmd' : 'npm'
+ const child = spawn(npmBin, [
+ 'config', 'ls', '--json', '-l'
+ // We add argv here to get npm to parse those options for us :D
+ ].concat(argv || []), {
+ env: process.env,
+ cwd: process.cwd(),
+ stdio: [0, 'pipe', 2]
+ })
+
+ let stdout = ''
+ if (child.stdout) {
+ child.stdout.on('data', (chunk) => {
+ stdout += chunk
+ })
+ }
+
+ return await new Promise((resolve, reject) => {
+ child.on('error', reject)
+ child.on('close', (code) => {
+ if (code === 127) {
+ reject(new Error('`npm` command not found. Please ensure you have npm@5.4.0 or later installed.'))
+ } else {
+ try {
+ resolve(frogConfig(JSON.parse(stdout)))
+ } catch (e) {
+ reject(new Error('`npm config ls --json` failed to output json. Please ensure you have npm@5.4.0 or later installed.'))
+ }
+ }
+ })
+ })
+}