Wrap Directory.watch on linux for the watcher package.

pkg/watcher/test/no_subscription_test.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 'dart:async';
-
-import 'package:scheduled_test/scheduled_test.dart';
-import 'package:watcher/watcher.dart';
-
-import 'utils.dart';
-
-main() {
-  initConfig();
-
-  setUp(createSandbox);
-
-  test('does not notify for changes when there were no subscribers', () {
-    // Note that this test doesn't rely as heavily on the test functions in
-    // utils.dart because it needs to be very explicit about when the event
-    // stream is and is not subscribed.
-    var watcher = createWatcher();
-
-    // Subscribe to the events.
-    var completer = new Completer();
-    var subscription = watcher.events.listen(wrapAsync((event) {
-      expect(event.type, equals(ChangeType.ADD));
-      expect(event.path, endsWith("file.txt"));
-      completer.complete();
-    }));
-
-    writeFile("file.txt");
-
-    // Then wait until we get an event for it.
-    schedule(() => completer.future);
-
-    // Unsubscribe.
-    schedule(() {
-      subscription.cancel();
-    });
-
-    // Now write a file while we aren't listening.
-    writeFile("unwatched.txt");
-
-    // Then start listening again.
-    schedule(() {
-      completer = new Completer();
-      subscription = watcher.events.listen(wrapAsync((event) {
-        // We should get an event for the third file, not the one added while
-        // we weren't subscribed.
-        expect(event.type, equals(ChangeType.ADD));
-        expect(event.path, endsWith("added.txt"));
-        completer.complete();
-      }));
-    });
-
-    // The watcher will have been cancelled and then resumed in the middle of
-    // its pause between polling loops. That means the second scan to skip
-    // what changed while we were unsubscribed won't happen until after that
-    // delay is done. Wait long enough for that to happen.
-    //
-    // We're doing * 4 here because that seems to give the slower bots enough
-    // time for this to complete.
-    schedule(() => new Future.delayed(watcher.pollingDelay * 4));
-
-    // And add a third file.
-    writeFile("added.txt");
-
-    // Wait until we get an event for the third file.
-    schedule(() => completer.future);
-
-    schedule(() {
-      subscription.cancel();
-    });
-  });
-}