Roll Observatory packages and add a roll script

packages/quiver/test/streams/enumerate_test.dart

+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+library quiver.streams.enumerate_test;
+
+import 'dart:async';
+
+import 'package:test/test.dart';
+import 'package:quiver/streams.dart';
+
+main() {
+  group('enumerate', () {
+    test('should add indices to its argument', () {
+      var controller = new StreamController<String>();
+      var enumerated = enumerate(controller.stream);
+      var expectation = enumerated.toList().then((e) {
+        expect(e.map((v) => v.index), [0, 1, 2]);
+        expect(e.map((v) => v.value), ['a', 'b', 'c']);
+      });
+      ['a', 'b', 'c'].forEach(controller.add);
+      return Future.wait([controller.close(), expectation]);
+    });
+  });
+}