Use stream matchers to unflake the mac OS watcher tests.

pkg/watcher/test/directory_watcher/mac_os_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:scheduled_test/scheduled_test.dart';
 import 'package:watcher/src/directory_watcher/mac_os.dart';
 import 'package:watcher/watcher.dart';
 
 import 'shared.dart';
 import '../utils.dart';
@@ skipping 20 matching lines @@
     deleteDir("dir");
     createDir("dir");
 
     startWatcher(dir: "dir");
     writeFile("dir/newer.txt");
     expectAddEvent("dir/newer.txt");
   });
 
   test('emits events for many nested files moved out then immediately back in',
       () {
+    // TODO(nweiz): re-enable this when issue 16003 is fixed.
+    return;

[Bob Nystrom, 2014/01/09 22:49:20]

I think this generates an unreachable code warning in the Editor. Also, this
will still print the test in the output I'd just comment out the whole test.

[nweiz, 2014/01/10 01:05:31]

Done.

+
     withPermutations((i, j, k) =>
         writeFile("dir/sub/sub-$i/sub-$j/file-$k.txt"));
 
     startWatcher(dir: "dir");
 
     renameDir("dir/sub", "sub");
     renameDir("sub", "dir/sub");
 
-    inAnyOrder(() {
-      withPermutations((i, j, k) =>
-          expectRemoveEvent("dir/sub/sub-$i/sub-$j/file-$k.txt"));
-    });
+    allowEither(() {
+      inAnyOrder(withPermutations((i, j, k) =>
+          isRemoveEvent("dir/sub/sub-$i/sub-$j/file-$k.txt")));
 
-    inAnyOrder(() {
-      withPermutations((i, j, k) =>
-          expectAddEvent("dir/sub/sub-$i/sub-$j/file-$k.txt"));
+      inAnyOrder(withPermutations((i, j, k) =>
+          isAddEvent("dir/sub/sub-$i/sub-$j/file-$k.txt")));
+    }, () {
+      inAnyOrder(withPermutations((i, j, k) =>
+          isModifyEvent("dir/sub/sub-$i/sub-$j/file-$k.txt")));
     });
   });
 }