Roll Observatory packages and add a roll script

packages/quiver/test/iterables/range_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.range_test;
+
+import 'package:test/test.dart';
+import 'package:quiver/iterables.dart';
+
+main() {
+  group('range', () {
+    test("should create an empty iterator if stop is 0", () {
+      expect(range(0), []);
+    });
+
+    test("should create a sequence from 0 to stop - 1", () {
+      expect(range(10), [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
+    });
+
+    test("should start sequences at start_or_stop", () {
+      expect(range(1, 11), [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+    });
+
+    test("should create an empty iterator if start and stop are equal", () {
+      expect(range(1, 1), []);
+    });
+
+    test("should step by step", () {
+      expect(range(0, 10, 2), [0, 2, 4, 6, 8]);
+      expect(range(0, 10, 3), [0, 3, 6, 9]);
+    });
+
+    test("should step by a negative step", () {
+      expect(range(10, 0, -1), [10, 9, 8, 7, 6, 5, 4, 3, 2, 1]);
+      expect(range(0, -8, -1), [0, -1, -2, -3, -4, -5, -6, -7]);
+      expect(range(0, -10, -3), [0, -3, -6, -9]);
+    });
+
+    test("should throw with a bad range", () {
+      expect(() => range(10, 0), throws);
+    });
+
+    test("should throw with a bad step", () {
+      expect(() => range(0, 10, -1), throws);
+    });
+  });
+}