Fix race condition in Directory.create.

tests/standalone/io/directory_create_race_test.dart

Index: tests/standalone/io/directory_create_race_test.dart
diff --git a/tests/standalone/io/directory_create_race_test.dart b/tests/standalone/io/directory_create_race_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..9e9be58486f3f4307c90a44e15640df6e698bae0
--- /dev/null
+++ b/tests/standalone/io/directory_create_race_test.dart
@@ -0,0 +1,43 @@
+// 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.
+//
+// Test for a race condition that can occur when recursively creating
+// a directory multiple times simultaneously.  This consistently reproduces
+// issue https://code.google.com/p/dart/issues/detail?id=7679 in revisions
+// without the fix for this issue.
+
+import "dart:async";
+import "dart:io";
+import "dart:isolate";
+
+void testCreateRecursiveRace() {
+  var keepAlive = new ReceivePort();
+  var temp = new Directory('').createTempSync();
+  var d = new Directory('${temp.path}/a/b/c/d/e');
+  Futures.wait([
+      d.create(recursive: true),
+      d.create(recursive: true),
+      d.create(recursive: true),
+      d.create(recursive: true),
+      d.create(recursive: true),
+      d.create(recursive: true),
+      d.create(recursive: true),
+      d.create(recursive: true),
+      d.create(recursive: true),
+      d.create(recursive: true)]).then((_) {
+    Expect.isTrue(new Directory('${temp.path}/a').existsSync());
+    Expect.isTrue(new Directory('${temp.path}/a/b').existsSync());
+    Expect.isTrue(new Directory('${temp.path}/a/b/c').existsSync());
+    Expect.isTrue(new Directory('${temp.path}/a/b/c/d').existsSync());
+    Expect.isTrue(new Directory('${temp.path}/a/b/c/d/e').existsSync());
+    temp.delete(recursive: true).then((_) {
+      keepAlive.close();
+    });
+  });
+}
+
+void main() {
+  testCreateRecursiveRace();
+  testCreateRecursiveRace();
+}