Add a simple test for HTMLOptionsCollection.

tests/html/htmloptionscollection_test.dart

+// Copyright (c) 2012, 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('HTMLOptionsCollectionTest');
+#import('../../lib/unittest/unittest.dart');
+#import('../../lib/unittest/html_config.dart');
+#import('dart:html');
+
+main() {
+  useHtmlConfiguration();
+
+  test('indexedAccessTest', () {
+    // FIXME: we need some massaging to dart:html to enable HTMLOptionsCollection.add
+    // and hence programatic building of collection.
+    final selectElement = new Element.html('''
+      <select>
+        <option value="0">Option0</option>
+        <option value="1">Option1</option>
+        <option value="2">Option2</option>
+      ''');
+    final optionsCollection = selectElement.options;
+
+    expect(optionsCollection[0].value, equals('0'));
+    expect(optionsCollection[1].value, equals('1'));
+    expect(optionsCollection[2].value, equals('2'));
+
+    expect(optionsCollection[0].text, equals('Option0'));
+    expect(optionsCollection[1].text, equals('Option1'));
+    expect(optionsCollection[2].text, equals('Option2'));
+
+    expect(() { optionsCollection[0] = 1; }, throws);
+
+    optionsCollection[0] = new OptionElement(value: '42', data: 'Option42');
+    expect(optionsCollection[0].value, equals('42'));
+    expect(optionsCollection[0].text, equals('Option42'));
+  });
+}