anchor.diff:  
   // TODO(nweiz): This and other top-level functions should throw exceptions if
   // they're called after the declarer has finished declaring.
  -/// Creates a new test case with the given description and body.
  +/// Creates a new test case with the given description (converted to a string)
  +/// and body.
   ///
   /// The description will be added to the descriptions of any surrounding
   /// [group]s. If [testOn] is passed, it's parsed as a [platform selector][]; the
  
positive.code: /// If multiple platforms match, the annotations apply in order as through
  /// they were in nested groups.
  void group(description, body(),
      {String testOn,
      Timeout timeout,
      skip,
      tags,
      Map<String, dynamic> onPlatform}) =>
    description == null
        ? _declarer.group(description, body,
            testOn: testOn, timeout: timeout, skip: skip, tags: tags)
        : _declarer.group(description.toString(), body,
            testOn: testOn, timeout: timeout, skip: skip, tags: tags);
  
  
  /// Registers a function to be run before tests.
  ///
  
negative.code: 
  /// Creates a group of tests.
  ///
  /// A group's description (converted to a string) is included in the descriptions
  /// of any tests or sub-groups it contains. [setUp] and [tearDown] are also scoped
  /// to the containing group.
  ///
  /// If [testOn] is passed, it's parsed as a [platform selector][]; the test will
  /// only be run on matching platforms.
  