Wrap Directory.watch on Mac OS for the watcher package.

pkg/watcher/test/directory_watcher/mac_os_test.dart

Index: pkg/watcher/test/directory_watcher/mac_os_test.dart
diff --git a/pkg/watcher/test/directory_watcher/linux_test.dart b/pkg/watcher/test/directory_watcher/mac_os_test.dart
similarity index 69%
copy from pkg/watcher/test/directory_watcher/linux_test.dart
copy to pkg/watcher/test/directory_watcher/mac_os_test.dart
index ba695698b64c4b7a5e9d6d431343b87db2b638b9..f7f8176ae33385399a75dfd13bf69dc99fea29bd 100644
--- a/pkg/watcher/test/directory_watcher/linux_test.dart
+++ b/pkg/watcher/test/directory_watcher/mac_os_test.dart
@@ -3,7 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:scheduled_test/scheduled_test.dart';
-import 'package:watcher/src/directory_watcher/linux.dart';
+import 'package:watcher/src/directory_watcher/mac_os.dart';
 import 'package:watcher/watcher.dart';
 
 import 'shared.dart';
@@ -12,22 +12,27 @@ import '../utils.dart';
 main() {
   initConfig();
 
-  watcherFactory = (dir) => new LinuxDirectoryWatcher(dir);
+  watcherFactory = (dir) => new MacOSDirectoryWatcher(dir);
 
-  setUp(() {
-    // Increase the timeout because closing a [Directory.watch] stream blocks
-    // the main isolate for a very long time on Goobuntu, as of kernel
-    // 3.2.5-gg1336 (see issue 14606).
-    currentSchedule.timeout *= 3;
-
-    createSandbox();
-  });
+  setUp(createSandbox);
 
   sharedTests();
 
-  test('DirectoryWatcher creates a LinuxDirectoryWatcher on Linux', () {
+  test('DirectoryWatcher creates a MacOSDirectoryWatcher on Mac OS', () {
     expect(new DirectoryWatcher('.'),
-        new isInstanceOf<LinuxDirectoryWatcher>());
+        new isInstanceOf<MacOSDirectoryWatcher>());
+  });
+
+  test('does not notify about the watched directory being deleted and '
+      'recreated immediately before watching', () {
+    createDir("dir");
+    writeFile("dir/old.txt");
+    deleteDir("dir");
+    createDir("dir");
+
+    startWatcher(dir: "dir");
+    writeFile("dir/newer.txt");
+    expectAddEvent("dir/newer.txt");
   });
 
   test('notifies even if the file contents are unchanged', () {