Roll Observatory packages and add a roll script

packages/quiver/test/streams/collect_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.collect_test;
+
+import 'dart:async';
+import 'dart:math';
+
+import 'package:test/test.dart';
+import 'package:quiver/streams.dart';
+
+main() {
+  group('collect', () {
+    test('should produce no events for no futures',
+        () => collect([]).toList().then((events) => expect(events, isEmpty)));
+
+    test('should produce events for future completions in input order', () {
+      var futures = new Iterable.generate(
+          5, (int i) => i.isEven ? new Future.value(i) : new Future.error(i));
+      var events = [];
+      var done = new Completer();
+
+      collect(futures).listen(events.add, onError: (i) {
+        events.add('e$i');
+      }, onDone: done.complete);
+      return Future.wait(futures).catchError((_) => done.future).then((_) {
+        expect(events, [0, 'e1', 2, 'e3', 4]);
+      });
+    });
+
+    test('should only advance iterator once '
+        'event for previous future is sent', () {
+      var eventCount = 0;
+      var maxParallel = 0;
+      var currentParallel = 0;
+      var done = new Completer();
+      var futures = new Iterable.generate(3, (_) {
+        maxParallel = max(++currentParallel, maxParallel);
+        return new Future.value();
+      });
+
+      var collected = collect(futures);
+
+      decrementParallel(_) {
+        eventCount++;
+        currentParallel--;
+      }
+
+      collected.listen(decrementParallel,
+          onError: decrementParallel, onDone: done.complete);
+      return done.future.then((_) {
+        expect(maxParallel, 1);
+        expect(eventCount, 3);
+      });
+    });
+  });
+}