Improve NVM detection

bin/index.js

@@ -8,29 +8,15 @@ require('meow')(_pkg)
 
 var path = require('path')
 var async = require('async')
-var which = require('which')
 var semver = require('semver')
-var spawn = require('child_process').spawn
+var which = require('./which')
+var Switcher = require('./switcher')
 var nodeVersions = require('node-versions')
 
 function processExit (code) {
   return process.exit(code || 0)
 }
 
-function nodeSwitcher (nodeVersion) {
-  var binaries = {
-    n: [nodeVersion],
-    nvm: ['use', nodeVersion]
-  }
-
-  function switcher (binary) {
-    return spawn(binary, binaries[binary], { stdio: 'inherit' })
-  }
-
-  switcher.binaries = function () { return Object.keys(binaries) }
-  return switcher
-}
-
 var pkg
 
 try {
@@ -43,24 +29,21 @@ var nodeVersion = pkg.engines && pkg.engines.node
 if (!nodeVersion) processExit()
 
 var maxNodeVersion = semver.maxSatisfying(nodeVersions, nodeVersion)
-var switcher = nodeSwitcher(maxNodeVersion)
-
-var binaries = switcher.binaries()
-var switcherBinary = null
+var switcher = Switcher(maxNodeVersion)
+var switcherBin = null
 
-function getBinary (next) {
-  var binary = binaries.shift()
-  which(binary, function (err) {
-    if (!err) switcherBinary = binary
+function getBin (next) {
+  var bin = switcher.binaries.shift()
+  which(bin, function (err) {
+    if (!err) switcherBin = bin
     return next()
   })
 }
 
 function whileCondition () {
-  return switcherBinary != null && binaries.length !== 0
+  return switcherBin == null && switcher.binaries.length !== 0
 }
 
-async.doWhilst(getBinary, whileCondition, function () {
-  if (switcherBinary) return switcher(switcherBinary)
-  return processExit()
+async.doWhilst(getBin, whileCondition, function () {
+  if (switcherBin) return switcher(switcherBin)
 })

bin/switcher.js

@@ -0,0 +1,21 @@
+'use strict'
+
+var spawn = require('child_process').spawn
+
+function Switcher (version) {
+  var binArgs = {
+    n: ['n', version],
+    nvm: [process.env.SHELL, '-c', 'source $NVM_DIR/nvm.sh; nvm use ' + version]
+  }
+
+  function switcher (bin) {
+    var args = binArgs[bin]
+    bin = args.shift()
+    return spawn(bin, args, { stdio: 'inherit' })
+  }
+
+  switcher.binaries = Object.keys(binArgs)
+  return switcher
+}
+
+module.exports = Switcher

bin/which.js

@@ -0,0 +1,18 @@
+'use strict'
+
+var _which = require('which')
+var NVM_DIR = process.env.NVM_DIR
+
+function which (bin, cb) {
+  var binaries = {
+    n: function () { return _which(bin, cb) },
+    nvm: function () {
+      if (NVM_DIR) return process.nextTick(cb)
+      process.nextTick(function () { return cb('nope') })
+    }
+  }
+
+  return binaries[bin]()
+}
+
+module.exports = which