Prune user-namespaced modules

.gitignore

@@ -4,6 +4,7 @@
 *.pem
 node_modules
 test/fixtures/basic/main-link.js
+!test/fixtures/prune-is-module/node_modules
 test/work
 .DS_Store
 .nyc_output

prune.js

@@ -56,10 +56,16 @@ class Pruner {
   }
 }
 
+function isNodeModuleFolder (pathToCheck) {
+  return path.basename(path.dirname(pathToCheck)) === 'node_modules' ||
+    // TODO: Change to startsWith in Node 6
+    (path.basename(path.dirname(pathToCheck))[0] === '@' && path.basename(path.resolve(pathToCheck, `..${path.sep}..`)) === 'node_modules')
+}
+
 module.exports = {
   isModule: function isModule (pathToCheck) {
     return fs.pathExists(path.join(pathToCheck, 'package.json'))
-      .then(exists => exists && path.basename(path.dirname(pathToCheck)) === 'node_modules')
+      .then(exists => exists && isNodeModuleFolder(pathToCheck))
   },
   Pruner: Pruner
 }

test/prune.js

@@ -56,10 +56,13 @@ util.testSinglePlatform('prune electron in dependencies', (t, baseOpts) => {
 util.testSinglePlatform('prune: false test', createPruneOptionTest, false,
                         'package.json devDependency should exist under app/node_modules')
 
-test('isModule only detects modules inside a node_modules parent folder', t =>
+test('isModule properly detects module folders', t =>
   prune.isModule(util.fixtureSubdir(path.join('prune-is-module', 'node_modules', 'module')))
     .then(isModule => {
       t.true(isModule, 'module folder should be detected as module')
       return prune.isModule(util.fixtureSubdir(path.join('prune-is-module', 'node_modules', 'module', 'not-module')))
-    }).then(isModule => t.false(isModule, 'not-module folder should not be detected as module'))
+    }).then(isModule => {
+      t.false(isModule, 'not-module subfolder should not be detected as module')
+      return prune.isModule(util.fixtureSubdir(path.join('prune-is-module', 'node_modules', '@user', 'namespaced')))
+    }).then(isModule => t.true(isModule, '@user/namespaced folder should be detected as module'))
 )