Install barback from a hosted source in all tests.

test/transformer/exclusion/works_on_aggregate_transformer_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS d.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 pub_tests;
 
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 import '../../serve/utils.dart';
 
@@ skipping 19 matching lines @@
       var id = new AssetId(transform.package,
           p.url.join(transform.key, 'out.txt'));
       transform.addOutput(new Asset.fromString(id, contents.join('\\n')));
     });
   }
 }
 """;
 
 main() {
   integration("works on an aggregate transformer", () {
+    serveBarback();
+
     d.dir(appPath, [
       d.pubspec({
         "name": "myapp",
         "transformers": [
           {
             "myapp": {
               "\$include": ["web/a.txt", "web/b.txt", "web/c.txt"],
               "\$exclude": "web/a.txt"
             }
           }
-        ]
+        ],
+        "dependencies": {"barback": "any"}
       }),
       d.dir("lib", [
         d.file("transformer.dart", AGGREGATE_TRANSFORMER),
       ]),
       d.dir("web", [
         d.file("a.txt", "a"),
         d.file("b.txt", "b"),
         d.file("c.txt", "c"),
         d.file("d.txt", "d")
       ])
     ]).create();
 
-    createLockFile('myapp', pkg: ['barback']);
-
+    pubGet();
     pubServe();
     requestShouldSucceed("out.txt", "b\nc");
     endPubServe();
   });
 }