diff -r 000000000000 -r 6474c204b198 xpcom/tests/unit/test_file_renameTo.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/tests/unit/test_file_renameTo.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,61 @@
+/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+
+function run_test()
+{
+  // Create the base directory.
+  let base = Cc['@mozilla.org/file/directory_service;1']
+             .getService(Ci.nsIProperties)
+             .get('TmpD', Ci.nsILocalFile);
+  base.append('renameTesting');
+  if (base.exists()) {
+    base.remove(true);
+  }
+  base.create(Ci.nsIFile.DIRECTORY_TYPE, parseInt('0777', 8));
+
+  // Create a sub directory under the base.
+  let subdir = base.clone();
+  subdir.append('subdir');
+  subdir.create(Ci.nsIFile.DIRECTORY_TYPE, parseInt('0777', 8));
+
+  // Create a file under the sub directory.
+  let tempFile = subdir.clone();
+  tempFile.append('file0.txt');
+  tempFile.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, parseInt('0777', 8));
+
+  // Test renameTo in the base directory
+  tempFile.renameTo(null, 'file1.txt');
+  do_check_true(exists(subdir, 'file1.txt'));
+
+  // Test moving across directories
+  tempFile = subdir.clone();
+  tempFile.append('file1.txt');
+  tempFile.renameTo(base, '');
+  do_check_true(exists(base, 'file1.txt'));
+
+  // Test moving across directories and renaming at the same time
+  tempFile = base.clone();
+  tempFile.append('file1.txt');
+  tempFile.renameTo(subdir, 'file2.txt');
+  do_check_true(exists(subdir, 'file2.txt'));
+
+  // Test moving a directory
+  subdir.renameTo(base, 'renamed');
+  do_check_true(exists(base, 'renamed'));
+  let renamed = base.clone();
+  renamed.append('renamed');
+  do_check_true(exists(renamed, 'file2.txt'));
+
+  base.remove(true);
+}
+
+function exists(parent, filename) {
+  let file = parent.clone();
+  file.append(filename);
+  return file.exists();
+}