Install barback from a hosted source in all tests.

test/transformer/exclusion/works_on_transformer_group_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';
 
 const GROUP = """
 import 'package:barback/barback.dart';
 
 import 'transformer.dart';
 
 class RewriteGroup implements TransformerGroup {
   RewriteGroup.asPlugin();
 
   Iterable<Iterable> get phases => [[new RewriteTransformer.asPlugin()]];
 }
 """;
 
 main() {
    integration("works on a transformer group", () {
+     serveBarback();
+
      d.dir(appPath, [
        d.pubspec({
          "name": "myapp",
          "transformers": [
            {
              "myapp/src/group": {
                "\$include": ["web/a.txt", "web/b.txt"],
                "\$exclude": "web/a.txt"
              }
            }
-         ]
+         ],
+         "dependencies": {"barback": "any"}
        }),
        d.dir("lib", [d.dir("src", [
          d.file("transformer.dart", REWRITE_TRANSFORMER),
          d.file("group.dart", GROUP)
        ])]),
        d.dir("web", [
          d.file("a.txt", "a.txt"),
          d.file("b.txt", "b.txt"),
          d.file("c.txt", "c.txt")
        ])
      ]).create();
 
-     createLockFile('myapp', pkg: ['barback']);
-
+     pubGet();
      pubServe();
      requestShould404("a.out");
      requestShouldSucceed("b.out", "b.txt.out");
      requestShould404("c.out");
      endPubServe();
    });
 }