feature: tag tests; choose tags on command line

lib/src/backend/declarer.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 test.backend.declarer;
 
 import 'dart:async';
 
 import '../frontend/timeout.dart';
 import '../utils.dart';
@@ skipping 55 matching lines @@
 
   Declarer._(this._parent, this._name, this._metadata);
 
   /// Runs [body] with this declarer as [Declarer.current].
   ///
   /// Returns the return value of [body].
   declare(body()) => runZoned(body, zoneValues: {#test.declarer: this});
 
   /// Defines a test case with the given name and body.
   void test(String name, body(), {String testOn, Timeout timeout, skip,
-      Map<String, dynamic> onPlatform}) {
+      Map<String, dynamic> onPlatform, List<String> tags}) {
     _checkNotBuilt("test");
 
     var metadata = _metadata.merge(new Metadata.parse(
-        testOn: testOn, timeout: timeout, skip: skip, onPlatform: onPlatform));
+        testOn: testOn, timeout: timeout, skip: skip, onPlatform: onPlatform,
+        tags: tags));
 
     _entries.add(new LocalTest(_prefix(name), metadata, () {
       // TODO(nweiz): It might be useful to throw an error here if a test starts
       // running while other tests from the same declarer are also running,
       // since they might share closurized state.
 
       // TODO(nweiz): Use async/await here once issue 23497 has been fixed in
       // two stable versions.
       return Invoker.current.waitForOutstandingCallbacks(() {
         return _runSetUps().then((_) => body());
       }).then((_) => _runTearDowns());
     }));
   }
 
   /// Creates a group of tests.
   void group(String name, void body(), {String testOn, Timeout timeout, skip,
-      Map<String, dynamic> onPlatform}) {
+      Map<String, dynamic> onPlatform, List<String> tags}) {
     _checkNotBuilt("group");
 
     var metadata = _metadata.merge(new Metadata.parse(
-        testOn: testOn, timeout: timeout, skip: skip, onPlatform: onPlatform));
+        testOn: testOn, timeout: timeout, skip: skip, onPlatform: onPlatform,
+        tags: tags));
 
     // Don't load the tests for a skipped group.
     if (metadata.skip) {
       _entries.add(new Group(name, [], metadata: metadata));
       return;
     }
 
     var declarer = new Declarer._(this, _prefix(name), metadata);
     declarer.declare(body);
     _entries.add(declarer.build());
@@ skipping 107 matching lines @@
     var completer = new Completer();
 
     Invoker.current.addOutstandingCallback();
     Invoker.current.waitForOutstandingCallbacks(() {
       new Future.sync(body).whenComplete(completer.complete);
     }).then((_) => Invoker.current.removeOutstandingCallback());
 
     return completer.future;
   }
 }