[refactor] sync: check existence of node_modules

This brings the same perf improvements as in 4cf8928 / #190

Author: keithamus

lib/sync.js

@@ -164,10 +164,12 @@ module.exports = function (x, options) {
         var dirs = nodeModulesPaths(start, opts, x);
         for (var i = 0; i < dirs.length; i++) {
             var dir = dirs[i];
-            var m = loadAsFileSync(path.join(dir, '/', x));
-            if (m) return m;
-            var n = loadAsDirectorySync(path.join(dir, '/', x));
-            if (n) return n;
+            if (isDirectory(dir)) {
+                var m = loadAsFileSync(path.join(dir, '/', x));
+                if (m) return m;
+                var n = loadAsDirectorySync(path.join(dir, '/', x));
+                if (n) return n;
+            }
         }
     }
 };

test/mock_sync.js

@@ -10,6 +10,7 @@ test('mock', function (t) {
 
     var dirs = {};
     dirs[path.resolve('/foo/bar')] = true;
+    dirs[path.resolve('/foo/node_modules')] = true;
 
     function opts(basedir) {
         return {
@@ -56,6 +57,7 @@ test('mock package', function (t) {
 
     var dirs = {};
     dirs[path.resolve('/foo')] = true;
+    dirs[path.resolve('/foo/node_modules')] = true;
 
     function opts(basedir) {
         return {