Add the ability to add tags in the test config.

test/backend/metadata_test.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.
 
 import 'package:test/src/backend/metadata.dart';
 import 'package:test/src/backend/test_platform.dart';
 import 'package:test/src/frontend/timeout.dart';
 import 'package:test/src/frontend/skip.dart';
 import 'package:test/test.dart';
 
@@ skipping 50 matching lines @@
     });
 
     test("returns the normal metadata if forTag doesn't match tags", () {
       var metadata = new Metadata(
           verboseTrace: true,
           tags: ['bar', 'baz'],
           forTag: {'foo': new Metadata(skip: true)});
 
       expect(metadata.verboseTrace, isTrue);
       expect(metadata.skip, isFalse);
-      expect(metadata.tags, ['bar', 'baz']);
+      expect(metadata.tags, unorderedEquals(['bar', 'baz']));
       expect(metadata.forTag, contains('foo'));
       expect(metadata.forTag['foo'].skip, isTrue);
     });
 
     test("resolves forTags that match tags", () {
       var metadata = new Metadata(
           verboseTrace: true,
           tags: ['foo', 'bar', 'baz'],
           forTag: {
             'foo': new Metadata(skip: true),
             'baz': new Metadata(timeout: Timeout.none),
             'qux': new Metadata(skipReason: "blah")
           });
 
       expect(metadata.verboseTrace, isTrue);
       expect(metadata.skip, isTrue);
       expect(metadata.skipReason, isNull);
       expect(metadata.timeout, equals(Timeout.none));
-      expect(metadata.tags, equals(['foo', 'bar', 'baz']));
+      expect(metadata.tags, unorderedEquals(['foo', 'bar', 'baz']));
       expect(metadata.forTag.keys, equals(['qux']));
     });
 
+    test("resolves forTags that adds a behavioral tag", () {
+      var metadata = new Metadata(
+          tags: ['foo'],
+          forTag: {
+            'baz': new Metadata(skip: true),
+            'bar': new Metadata(verboseTrace: true, tags: ['baz']),
+            'foo': new Metadata(tags: ['bar'])
+          });
+
+      expect(metadata.verboseTrace, isTrue);
+      expect(metadata.skip, isTrue);
+      expect(metadata.tags, unorderedEquals(['foo', 'bar', 'baz']));
+      expect(metadata.forTag, isEmpty);
+    });
+
+    test("resolves forTags that adds circular tags", () {
+      var metadata = new Metadata(
+          tags: ['foo'],
+          forTag: {
+            'foo': new Metadata(tags: ['bar']),
+            'bar': new Metadata(tags: ['baz']),
+            'baz': new Metadata(tags: ['foo'])
+          });
+
+      expect(metadata.tags, unorderedEquals(['foo', 'bar', 'baz']));
+      expect(metadata.forTag, isEmpty);
+    });
+
     test("base metadata takes precedence over forTags", () {
       var metadata = new Metadata(
           verboseTrace: true,
           tags: ['foo'],
           forTag: {'foo': new Metadata(verboseTrace: false)});
 
       expect(metadata.verboseTrace, isTrue);
     });
   });
 
@@ skipping 44 matching lines @@
       }, throwsArgumentError);
     });
 
     test("refuses multiple Skips", () {
       expect(() {
         new Metadata.parse(onPlatform: {"chrome": [new Skip(), new Skip()]});
       }, throwsArgumentError);
     });
   });
 }