Add a testOn parameter to test() and group().

lib/src/backend/group.dart

 // Copyright (c) 2015, 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 unittest.backend.group;
 
 import 'dart:async';
 
 import '../utils.dart';
+import 'metadata.dart';
 
 /// A group contains multiple tests and subgroups.
 ///
 /// A group has a description that is prepended to that of all nested tests and
 /// subgroups. It also has [setUp] and [tearDown] functions which are scoped to
 /// the tests and groups it contains.
 class Group {
   /// The parent group, or `null` if this is the root group.
   final Group parent;
 
   /// The description of the current test group, or `null` if this is the root
   /// group.
   final String _description;
 
+  /// The metadata for this group, including the metadata of any parent groups.
+  Metadata get metadata {
+    if (parent == null) return _metadata;
+    return parent.metadata.merge(_metadata);
+  }
+  final Metadata _metadata;
+
   /// The set-up function for this group, or `null`.
   AsyncFunction setUp;
 
   /// The tear-down function for this group, or `null`.
   AsyncFunction tearDown;
 
   /// Returns the description for this group, including the description of any
   /// parent groups.
   ///
   /// If this is the root group, returns `null`.
   String get description {
     if (parent == null || parent.description == null) return _description;
     return "${parent.description} $_description";
   }
 
   /// Creates a new root group.
   ///
   /// This is the implicit group that exists outside of any calls to `group()`.
   Group.root()
-      : this(null, null);
+      : this(null, null, new Metadata());
 
-  Group(this.parent, this._description);
+  Group(this.parent, this._description, this._metadata);
 
   /// Run the set-up functions for this and any parent groups.
   ///
   /// If no set-up functions are declared, this returns a [Future] that
   /// completes immediately.
   Future runSetUp() {
     if (parent != null) {
       return parent.runSetUp().then((_) {
         if (setUp != null) return setUp();
       });
@@ skipping 11 matching lines @@
     if (parent != null) {
       return new Future.sync(() {
         if (tearDown != null) return tearDown();
       }).then((_) => parent.runTearDown());
     }
 
     if (tearDown != null) return new Future.sync(tearDown);
     return new Future.value();
   }
 }