Use the polling watcher by default in pub tests for now.

sdk/lib/_internal/pub/lib/src/barback/sources.dart

Index: sdk/lib/_internal/pub/lib/src/barback/sources.dart
diff --git a/sdk/lib/_internal/pub/lib/src/barback/sources.dart b/sdk/lib/_internal/pub/lib/src/barback/sources.dart
index c85044b75a82e413e6e653e01e327d5d2213ee04..0f44e76336f494d7894e5fa0d59f9a7466a6493a 100644
--- a/sdk/lib/_internal/pub/lib/src/barback/sources.dart
+++ b/sdk/lib/_internal/pub/lib/src/barback/sources.dart
@@ -18,9 +18,13 @@ import '../package_graph.dart';
 /// Adds all of the source assets in the provided packages to barback and
 /// then watches the public directories for changes.
 ///
-/// Returns a Future that completes when the sources are loaded and the
-/// watchers are active.
-Future watchSources(PackageGraph graph, Barback barback) {
+/// [watcherFactory] should return a [DirectoryWatcher] watching the given
+/// directory for changes.
+///
+/// Returns a Future that completes when the sources are loaded and the watchers
+/// are active.
+Future watchSources(PackageGraph graph, Barback barback,
+    DirectoryWatcher watcherFactory(String directory)) {

[Bob Nystrom, 2013/11/08 01:32:32]

Why not just pass the WatcherType in here?

[nweiz, 2013/11/08 01:44:24]

It seemed a little weird to have this just not handle WatcherType.NONE at all,
but done.

   return Future.wait(graph.packages.values.map((package) {
     // If this package comes from a cached source, its contents won't change so
     // we don't need to monitor it. `packageId` will be null for the application
@@ -39,7 +43,7 @@ Future watchSources(PackageGraph graph, Barback barback) {
       if (!dirExists(subdirectory)) return new Future.value();
 
       // TODO(nweiz): close these watchers when [barback] is closed.
-      var watcher = new DirectoryWatcher(subdirectory);
+      var watcher = watcherFactory(subdirectory);
       watcher.events.listen((event) {
         // Don't watch files symlinked into these directories.
         // TODO(rnystrom): If pub gets rid of symlinks, remove this.