feat(prepare): allow prefetching of only specified deps

lib/commands/prepare.js

@@ -1,9 +1,9 @@
 'use strict'
 
 const Prepare = module.exports = {
- command: 'prepare',
+ command: 'prepare [packages...]',
  aliases: ['prep'],
- describe: 'pre-fetch all dependencies',
+ describe: 'pre-fetch dependencies, or only the listed ones',
  builder (y) {
  return y.help().alias('help', 'h').options(Prepare.options)
  },
@@ -32,7 +32,8 @@ async function prepare (argv) {
  await installer({
  log (level, ...args) {
  return log[level](...args)
- }
+ },
+ only: argv.packages
  })
  } catch (e) {
  log.error('installer', e)

lib/installer.js

@@ -43,6 +43,7 @@ class Installer {
  this.log = this.opts.log ||
  ((level, type, ...msgs) => process.emit(level, type, ...msgs))
 
+ this.onlyDeps = opts.only && new Set(opts.only)
  this.pkg = null
  this.tree = null
  this.validLockHash = false
@@ -136,6 +137,13 @@ class Installer {
  )
  await this.checkLock()
  this.tree = buildLogicalTree(this.pkg, this.pkg._shrinkwrap)
+ if (this.onlyDeps) {
+ for (const [key, dep] of this.tree.dependencies.entries()) {
+ if (!this.onlyDeps.has(key)) {
+ this.tree.delDep(dep)
+ }
+ }
+ }
  this.log('silly', 'tree', this.tree)
  this.expectedTotal = 0
  this.tree.forEach((dep, next) => {