anchor.diff:   *
    * Multiple tests, grouped by category:
    *
  - *     #import('path-to-dart/pkg/unittest/unitest.dart');
  + *     import 'package:unittest/unittest.dart';
    *     main() {
    *       group('group A', () {
    *         test('test A.1', () {
  
positive.code:  * arguments or that take named parameters. (this is not implemented yet,
   * but will be coming here soon).
   *
   *     #import('path-to-dart/pkg/unittest/unitest.dart');
   *     #import('dart:html');
   *     main() {
   *       test('calllback is executed', () {
   *         // indicate ahead of time that an async callback is expected.
   *         var async = startAsync();
   *         window.setTimeout(() {
   *           // Guard the body of the callback, so errors are propagated
   *           // correctly
   *           guardAsync(() {
   *             int x = 2 + 3;
   *             expect(x, equals(5));
   *           });
   *           // indicate that the asynchronous callback was invoked.
   *           async.complete();
   *         }), 0);
   *       });
   *
   */
  library unittest;
  
negative.code: /**
   * A library for writing dart unit tests.
   *
   * To import this library, use the pub package manager.
   * Create a pubspec.yaml file in your project and add
   * a dependency on unittest with the following lines:
   *     dependencies:
   *       unittest:
   *         sdk: unittest
   *         
   * Then run 'pub install' from your project directory or using
   * the DartEditor.
   *         
   * Please see [Pub Getting Started](http://pub.dartlang.org/doc)
   * for more details about the pub package manager.
   *
   * ##Concepts##
   *
  