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packages/quiver/test/iterables/merge_test.dart

Index: packages/quiver/test/iterables/merge_test.dart
diff --git a/packages/quiver/test/iterables/merge_test.dart b/packages/quiver/test/iterables/merge_test.dart
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+// 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.merge_test;
+
+import 'package:test/test.dart';
+import 'package:quiver/iterables.dart';
+
+main() {
+  group('merge', () {
+    test("should merge no iterables into empty iterable", () {
+      expect(merge([]), []);
+    });
+
+    test("should merge empty iterables into empty iterable", () {
+      expect(merge([[]]), []);
+      expect(merge([[], []]), []);
+      expect(merge([[], [], []]), []);
+      for (int i = 4; i <= 10; i++) {
+        expect(merge(new List.filled(i, const [])), []);
+      }
+    });
+
+    test("should merge single-element iterables", () {
+      expect(merge([['a'], ['b']]), ['a', 'b']);
+    });
+
+    test("should output the union of elements in both iterables", () {
+      var a = ['a', 'b', 'c'];
+      expect(merge([a, a]), ['a', 'a', 'b', 'b', 'c', 'c']);
+    });
+
+    test("should honor the comparator", () {
+      var a = ['c', 'b', 'a'];
+      expect(merge([a, a], (x, y) => -x.compareTo(y)),
+          [ 'c', 'c', 'b', 'b', 'a', 'a' ]);
+    });
+
+    test("should merge empty iterables with non-empty ones", () {
+      var a = ['a', 'b', 'c'];
+      expect(merge([a, []]), ['a', 'b', 'c']);
+      expect(merge([[], a]), ['a', 'b', 'c']);
+    });
+
+    test("should throw on null elements", () {
+      var a = ['a', null, 'c'];
+      var b = ['a', 'b', 'c'];
+      expect(() => merge([a, b]).forEach((e) {}), throws);
+      expect(() => merge([b, a]).forEach((e) {}), throws);
+    });
+
+    test("should handle zig-zag case", () {
+      var a = ['a', 'a', 'd', 'f'];
+      var b = ['b', 'c', 'g', 'g'];
+      expect(merge([a, b]), ['a', 'a', 'b', 'c', 'd', 'f', 'g', 'g']);
+    });
+
+    test("should handle max(a) < min(b) case", () {
+      var a = <String>['a', 'b'];
+      var b = <String>['c', 'd'];
+      expect(max(a).compareTo(min(b)) < 0, isTrue); // test the test
+      expect(merge([a, b]), ['a', 'b', 'c', 'd']);
+    });
+
+    test("should handle three-way zig-zag case", () {
+      var a = ['a', 'd', 'g', 'j'];
+      var b = ['b', 'e', 'h', 'k'];
+      var c = ['c', 'f', 'i', 'l'];
+      var expected = [
+        'a', 'b', 'c',
+        'd', 'e', 'f',
+        'g', 'h', 'i',
+        'j', 'k', 'l'
+      ];
+      expect(merge([a, b, c]), expected);
+      expect(merge([a, c, b]), expected);
+      expect(merge([b, a, c]), expected);
+      expect(merge([b, c, a]), expected);
+      expect(merge([c, a, b]), expected);
+      expect(merge([c, b, a]), expected);
+    });
+  });
+}