Roll Observatory packages and add a roll script

packages/quiver/test/iterables/count_test.dart

+// Copyright 2013 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.iterables.count_test;
+
+import 'package:test/test.dart';
+import 'package:quiver/iterables.dart';
+
+main() {
+  group('count', () {
+    test("should create an infinite sequence starting at 0 given no args", () {
+      expect(count().first, 0);
+      expect(count().take(5), [0, 1, 2, 3, 4]);
+    });
+
+    test("should create an infinite sequence starting from start", () {
+      expect(count(3).first, 3);
+      expect(count(3).take(5), [3, 4, 5, 6, 7]);
+    });
+
+    test("should create an infinite sequence stepping by step", () {
+      expect(count(3, 2).first, 3);
+      expect(count(3, 2).take(5), [3, 5, 7, 9, 11]);
+      expect(count(3.5, 2).first, 3.5);
+      expect(count(3.5, .5).take(5), [3.5, 4, 4.5, 5, 5.5]);
+    });
+  });
+}