Install barback from a hosted source in all tests.

test/transformer/exclusion/works_on_lazy_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 'package:scheduled_test/scheduled_stream.dart';
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../../descriptor.dart' as d;
 import '../../test_pub.dart';
 import '../../serve/utils.dart';
 
 main() {
   integration("works on a lazy transformer", () {
+    serveBarback();
+
     d.dir(appPath, [
       d.pubspec({
         "name": "myapp",
         "transformers": [
           {
             "myapp": {
               "\$include": ["web/a.txt", "web/b.txt"],
               "\$exclude": "web/a.txt"
             }
           }
-        ]
+        ],
+        "dependencies": {"barback": "any"}
       }),
       d.dir("lib", [d.file("transformer.dart", LAZY_TRANSFORMER)]),
       d.dir("web", [
         d.file("a.txt", "a"),
         d.file("b.txt", "b"),
         d.file("c.txt", "c")
       ])
     ]).create();
 
-    createLockFile('myapp', pkg: ['barback']);
-
+    pubGet();
     var server = pubServe();
     // The transformer should remain lazy.
     server.stdout.expect("Build completed successfully");
 
     requestShould404("a.out");
     requestShouldSucceed("b.out", isNot(isEmpty));
     server.stdout.expect(consumeThrough(emitsLines(
         "[Info from LazyRewrite]:\n"
         "Rewriting myapp|web/b.txt.")));
     server.stdout.expect(consumeThrough("Build completed successfully"));
 
     requestShould404("c.out");
     endPubServe();
   });
 }