dart:io | Add rename to Link

tests/standalone/io/link_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import "package:expect/expect.dart";
 import "dart:async";
 import "dart:io";
 import "dart:isolate";
 
 // Test the dart:io Link class.
@@ skipping 155 matching lines @@
         .last)
   .then((_) =>
     // This directory listing must terminate, even though it contains loops.
     new Directory.fromPath(base.append('a/b/c'))
         .list(recursive: true, followLinks: true)
         .last)
   .then((_) =>
     new Directory.fromPath(base).delete(recursive: true));
 }
 
+testRenameSync() {
+  testRename(Path base, String target) {
+    Link link1 = new Link.fromPath(base.append('c'))..createSync(target);
+    Expect.isTrue(link1.existsSync());
+    Link link2 = link1.renameSync(base.append('d').toNativePath());
+    Expect.isFalse(link1.existsSync());
+    Expect.isTrue(link2.existsSync());
+    link2.deleteSync();
+    Expect.isFalse(link2.existsSync());
+  }
+
+  Directory baseDir = new Directory('').createTempSync();
+  Path base = new Path(baseDir.path);
+  Directory dir = new Directory.fromPath(base.append('a'))..createSync();
+  File file = new File.fromPath(base.append('b'))..createSync();
+
+  testRename(base, file.path);
+  testRename(base, dir.path);
+
+  baseDir.deleteSync(recursive: true);
+}
+
 void testLinkErrorSync() {
   Expect.throws(() =>
       new Link('some-dir-that-doent exist/some link file/bla/fisk').createSync(
           'bla bla bla/b lalal/blfir/sdfred/es'),
       (e) => e is LinkException);
 }
 
 main() {
   testCreateSync();
   testCreateLoopingLink();
+  testRenameSync();
   testLinkErrorSync();
 }