Install barback from a hosted source in all tests.

test/transformer/runs_a_transformer_on_a_dependency_test.dart

Index: test/transformer/runs_a_transformer_on_a_dependency_test.dart
diff --git a/test/transformer/runs_a_transformer_on_a_dependency_test.dart b/test/transformer/runs_a_transformer_on_a_dependency_test.dart
index f0fb434d69d00222ebd4f3e62b3486619c9bd8e4..e69bfcd85d0c4209b3e25eaf4a26f73ecc243d87 100644
--- a/test/transformer/runs_a_transformer_on_a_dependency_test.dart
+++ b/test/transformer/runs_a_transformer_on_a_dependency_test.dart
@@ -10,11 +10,14 @@ import '../serve/utils.dart';
 
 main() {
   integration("runs a local transformer on a dependency", () {
+    serveBarback();
+
     d.dir("foo", [
       d.pubspec({
         "name": "foo",
         "version": "0.0.1",
-        "transformers": ["foo/transformer"]
+        "transformers": ["foo/transformer"],
+        "dependencies": {"barback": "any"}
       }),
       d.dir("lib", [
         d.file("transformer.dart", REWRITE_TRANSFORMER),
@@ -26,8 +29,7 @@ main() {
       d.appPubspec({"foo": {"path": "../foo"}}),
     ]).create();
 
-    createLockFile('myapp', sandbox: ['foo'], pkg: ['barback']);
-
+    pubGet();
     pubServe();
     requestShouldSucceed("packages/foo/foo.out", "foo.out");
     endPubServe();