Add the ability to add tags in the test config.

test/backend/metadata_test.dart

Index: test/backend/metadata_test.dart
diff --git a/test/backend/metadata_test.dart b/test/backend/metadata_test.dart
index adc8e78969801d272971596071c8692b60eba771..6fc200a60746bbe78df304e1e11d66c6899c8799 100644
--- a/test/backend/metadata_test.dart
+++ b/test/backend/metadata_test.dart
@@ -68,7 +68,7 @@ void main() {
 
       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);
     });
@@ -87,10 +87,38 @@ void main() {
       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,