Install barback from a hosted source in all tests.

test/transformer/configuration/configuration_defaults_to_empty_map_test.dart

 // Copyright (c) 2013, 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 'dart:convert';
 
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
@@ skipping 17 matching lines @@
       var id = transform.primaryInput.id.changeExtension(".json");
       transform.addOutput(
           new Asset.fromString(id, JSON.encode(settings.configuration)));
     });
   }
 }
 """;
 
 main() {
    integration("configuration defaults to an empty map", () {
+     serveBarback();
+
      d.dir(appPath, [
        d.pubspec({
          "name": "myapp",
-         "transformers": ["myapp/src/transformer"]
+         "transformers": ["myapp/src/transformer"],
+         "dependencies": {"barback": "any"}
        }),
        d.dir("lib", [d.dir("src", [
          d.file("transformer.dart", transformer)
        ])]),
        d.dir("web", [
          d.file("foo.txt", "foo")
        ])
      ]).create();
 
-     createLockFile('myapp', pkg: ['barback']);
-
+     pubGet();
      var server = pubServe();
      requestShouldSucceed("foo.json", JSON.encode({}));
      endPubServe();
    });
 }