Install barback from a hosted source in all tests.

test/transformer/loads_a_declaring_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 25 matching lines @@
 
   void declareOutputs(DeclaringAggregateTransform transform) {
     transform.declareOutput(new AssetId(transform.package,
         p.url.join(transform.key, 'out.final')));
   }
 }
 """;
 
 main() {
   integration("loads a declaring aggregate transformer", () {
+    serveBarback();
+
     d.dir(appPath, [
       d.pubspec({
         "name": "myapp",
-        "transformers": ["myapp/lazy", "myapp/aggregate"]
+        "transformers": ["myapp/lazy", "myapp/aggregate"],
+        "dependencies": {"barback": "any"}
       }),
       d.dir("lib", [
         d.file("lazy.dart", LAZY_TRANSFORMER),
         d.file("aggregate.dart", AGGREGATE_TRANSFORMER),
       ]),
       d.dir("web", [
         d.file("foo.txt", "foo"),
         d.file("bar.txt", "bar")
       ])
     ]).create();
 
-    createLockFile('myapp', pkg: ['barback']);
-
+    pubGet();
     var server = pubServe();
     // The transformer should preserve laziness.
     server.stdout.expect("Build completed successfully");
 
     requestShouldSucceed("out.final", "bar.out\nfoo.out");
     endPubServe();
   });
 }