Treat add events for known files as modifications instead of discarding them on Mac OS. Fixes pub s…

test/directory_watcher/shared.dart

 // Copyright (c) 2012, 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/utils.dart';
 
 import '../utils.dart';
 
 void sharedTests() {
@@ skipping 103 matching lines @@
       expectAddEvent("dir/new.txt");
     });
 
     test('notifies when a file is moved outside the watched directory', () {
       writeFile("dir/old.txt");
       startWatcher(dir: "dir");
 
       renameFile("dir/old.txt", "new.txt");
       expectRemoveEvent("dir/old.txt");
     });
+
+    test('notifies when a file is moved onto an existing one', () {
+      writeFile("from.txt");
+      writeFile("to.txt");
+      startWatcher();
+
+      renameFile("from.txt", "to.txt");
+      inAnyOrder([
+        isRemoveEvent("from.txt"),
+        isModifyEvent("to.txt")
+      ]);
+    });
   });
 
   // Most of the time, when multiple filesystem actions happen in sequence,
   // they'll be batched together and the watcher will see them all at once.
   // These tests verify that the watcher normalizes and combine these events
   // properly. However, very occasionally the events will be reported in
   // separate batches, and the watcher will report them as though they occurred
   // far apart in time, so each of these tests has a "backup case" to allow for
   // that as well.
   group("clustered changes", () {
@@ skipping 155 matching lines @@
       deleteFile("dir/sub");
       renameDir("old", "dir/sub");
 
       var events = withPermutations((i, j, k)  =>
           isAddEvent("dir/sub/sub-$i/sub-$j/file-$k.txt"));
       events.add(isRemoveEvent("dir/sub"));
       inAnyOrder(events);
     });
   });
 }