add mutation observer polyfill package

pkg/mutation_observer/test/mutation_observer_test.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library mutation_observer_test;
+
+import 'dart:html';
+import 'package:unittest/unittest.dart';
+import 'package:unittest/html_individual_config.dart';
+
+main() {
+  useHtmlIndividualConfiguration();
+
+  // Load the MutationObserver polyfill.
+  HttpRequest.getString('/root_dart/pkg/mutation_observer/lib/'
+      'mutation_observer.min.js').then((code) {
+
+    // Force MutationObserver polyfill to be used so we can test it, even in
+    // browsers with native support.
+    document.head.children.add(new ScriptElement()
+        ..text = 'window.MutationObserver = void 0;'
+                 'window.WebKitMutationObserver = void 0;'
+                 '$code');
+
+    testMutationObserver();
+  });
+}
+
+/**
+ * Test suite for Mutation Observers. This is just a small set of sanity
+ * checks, not a complete test suite.
+ */
+testMutationObserver() {
+  group('supported', () {
+    test('supported', () {
+      expect(MutationObserver.supported, true, reason: 'polyfill loaded.');
+    });
+  });
+
+  group('childList', () {
+    mutationCallback(count, expectation) {
+      var done = false;
+      var nodes = [];
+
+      callback(mutations, observer) {
+        for (MutationRecord mutation in mutations) {
+          for (Node node in mutation.addedNodes) {
+            nodes.add(node);
+          }
+        }
+        if (nodes.length >= count) {
+          done = true;
+          expect(nodes.length, count);
+          expect(nodes, expectation);
+        }
+      }
+
+      return expectAsyncUntil2(callback, () => done);
+    }
+
+    test('empty options is syntax error', () {
+      var mutationObserver = new MutationObserver(
+          (mutations, observer) { expect(false, isTrue,
+              reason: 'Should not be reached'); });
+      expect(() { mutationObserver.observe(document, {}); },
+             throws);
+    });
+
+    test('direct-parallel options-named', () {
+      var container = new DivElement();
+      var div1 = new DivElement();
+      var div2 = new DivElement();
+      var mutationObserver = new MutationObserver(
+          mutationCallback(2, orderedEquals([div1, div2])));
+      mutationObserver.observe(container, childList: true);
+
+      container.append(div1);
+      container.append(div2);
+    });
+
+    test('direct-nested options-named', () {
+      var container = new DivElement();
+      var div1 = new DivElement();
+      var div2 = new DivElement();
+      var mutationObserver =
+          new MutationObserver(mutationCallback(1, orderedEquals([div1])));
+      mutationObserver.observe(container, childList: true);
+
+      container.append(div1);
+      div1.append(div2);
+    });
+
+    test('subtree options-named', () {
+      var container = new DivElement();
+      var div1 = new DivElement();
+      var div2 = new DivElement();
+      var mutationObserver = new MutationObserver(
+          mutationCallback(2, orderedEquals([div1, div2])));
+      mutationObserver.observe(container, childList: true, subtree: true);
+
+      container.append(div1);
+      div1.append(div2);
+    });
+
+    test('mutation event', () {
+      var event = new MutationEvent('something', prevValue: 'prev',
+          newValue: 'new', attrName: 'attr');
+      expect(event is MutationEvent, isTrue);
+      expect(event.prevValue, 'prev');
+      expect(event.newValue, 'new');
+      expect(event.attrName, 'attr');
+    });
+  });
+}