Factor out extraneous and dev module detection into stand alone packages

3 files changed, 20 insertions, 8 deletions

diff --git a/lib/install/is-dev.js b/lib/install/is-dev.js
new file mode 100644
index 000000000..2bbf4478e
--- /dev/null
+++ b/lib/install/is-dev.js
@@ -0,0 +1,7 @@
+'use strict'
+var isDev = exports.isDev = function (node) {
+  return node.package._requiredBy.filter(function (req) { return req === '#DEV:/' }).length
+}
+exports.isOnlyDev = function (node) {
+  return node.package._requiredBy.length === 1 && isDev(node)
+}
diff --git a/lib/install/is-extraneous.js b/lib/install/is-extraneous.js
new file mode 100644
index 000000000..cf44a4826
--- /dev/null
+++ b/lib/install/is-extraneous.js
@@ -0,0 +1,11 @@
+'use strict'
+var isDev = require('./is-dev.js').isDev
+
+module.exports = function (tree) {
+  var pkg = tree.package
+  var requiredBy = pkg._requiredBy.filter(function (req) { return req[0] !== '#' })
+  var isTopLevel = tree.parent == null
+  var isChildOfTop = !isTopLevel && tree.parent.parent == null
+  var topHasNoPackageJson = isChildOfTop && tree.parent.package.name === undefined && tree.parent.package.version === undefined && tree.parent.package._id === undefined
+  return !isTopLevel && (!isChildOfTop || !topHasNoPackageJson) && requiredBy.length === 0 && !isDev(tree)
+}
diff --git a/lib/install/logical-tree.js b/lib/install/logical-tree.js
index 06c8a8183..e6c8d5c95 100644
--- a/lib/install/logical-tree.js
+++ b/lib/install/logical-tree.js
@@ -5,6 +5,7 @@ var without = require('lodash.without')
 var validate = require('aproba')
 var flattenTree = require('./flatten-tree.js')
 var npm = require('../npm.js')
+var isExtraneous = require('./is-extraneous.js')
 
 var logicalTree = module.exports = function (tree) {
   validate('O', arguments)
@@ -58,14 +59,7 @@ function translateTree (tree) {
   })
   pkg.path = tree.path
 
-  // All package-only requiredBys (exclude #USER and #EXISTING)
-  var requiredBy = pkg._requiredBy.filter(function (req) { return req[0] !== '#' })
-  var isDev = pkg._requiredBy.filter(function (req) { return req.substr(0,4) === '#DEV' }).length
-
-  var isTopLevel = tree.parent == null
-  var isChildOfTop = !isTopLevel && tree.parent.parent == null
-  var topHasNoPackageJson = isChildOfTop && tree.parent.package.name === undefined && tree.parent.package.version === undefined && tree.parent.package._id === undefined
-  pkg.extraneous = !isTopLevel && (!isChildOfTop || !topHasNoPackageJson) && requiredBy.length === 0 && !isDev
+  pkg.extraneous = isExtraneous(tree)
   if (tree.target && tree.parent && !tree.parent.target) pkg.link = tree.realpath
   return pkg
 }