Transition barback's infrastructure to an aggregate-based model.

pkg/barback/test/asset_set_test.dart

 // Copyright (c) 2013, 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 barback.test.asset_set_test;
 
 import 'package:barback/barback.dart';
 import 'package:unittest/unittest.dart';
 
 import 'utils.dart';
@@ skipping 128 matching lines @@
     });
 
     test("returns null when removing an asset not in the set", () {
       var set = new AssetSet();
       var foo = new Asset.fromString(fooId, "foo");
       set.add(foo);
 
       expect(set.removeId(barId), isNull);
     });
   });
+
+  group(".ids", () {
+    test("contains the ids of all the assets in the set", () {
+      var set = new AssetSet();
+      var foo = new Asset.fromString(fooId, "foo");
+      var bar = new Asset.fromString(barId, "bar");
+      set.addAll([foo, bar]);
+      expect(set.ids, unorderedEquals([fooId, barId]));
+    });
+  });
 }