Warn once through util.deprecate, refactor

Author: silverwind

lib/module.js

@@ -7,7 +7,6 @@ const assert = require('assert').ok;
 const fs = require('fs');
 const path = require('path');
 
-
 // If obj.hasOwnProperty has been overridden, then calling
 // obj.hasOwnProperty(prop) will break.
 // See: https://github.com/joyent/node/issues/1707
@@ -125,6 +124,11 @@ function tryExtensions(p, exts) {
 }
 
 
+const noopDeprecateRequireDot = util.deprecate(function() {},
+  `warning: require('.') did resolve outside the package directory. ` +
+  `This functionality will be deprecated soon.`);
+
+
 Module._findPath = function(request, paths) {
   var exts = Object.keys(Module._extensions);
 
@@ -169,9 +173,8 @@ Module._findPath = function(request, paths) {
     }
 
     if (filename) {
-      if (request === '.' && i > 0) {
-        console.error(`(node) warning: require('.') resolved to ${filename}`);
-      }
+      // Warn once if '.' resolved outside the module dir
+      if (request === '.' && i > 0) noopDeprecateRequireDot();
       Module._pathCache[cacheKey] = filename;
       return filename;
     }
@@ -215,11 +218,14 @@ Module._resolveLookupPaths = function(request, parent) {
       paths = parent.paths.concat(paths);
     }
 
-    // For '.', put the module's dir at the front of the resolve paths
-    // TODO(silverwind): Treat '.' exactly the same as './'
+    // Maintain backwards compat with certain broken uses of require('.')
+    // by putting the module's directory in front of the lookup paths.
     if (request === '.') {
-      paths.splice(0, 0, parent && parent.filename ?
-          path.dirname(parent.filename) : path.resolve(request));
+      if (parent && parent.filename) {
+        paths.splice(0, 0, path.dirname(parent.filename));
+      } else {
+        paths.splice(0, 0, path.resolve(request));
+      }
     }
 
     return [request, paths];