Install barback from a hosted source in all tests.

test/transformer/can_use_has_input_test.dart

Index: test/transformer/can_use_has_input_test.dart
diff --git a/test/transformer/can_use_has_input_test.dart b/test/transformer/can_use_has_input_test.dart
index 1e497445771e4516c4b541417c98d3cfddaa0865..61329d15406255159374eaf7d3a25052ad61b8c1 100644
--- a/test/transformer/can_use_has_input_test.dart
+++ b/test/transformer/can_use_has_input_test.dart
@@ -34,10 +34,13 @@ class RewriteTransformer extends Transformer {
 
 main() {
    integration("a transform can use hasInput", () {
+     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)
@@ -47,8 +50,7 @@ main() {
        ])
      ]).create();
 
-     createLockFile('myapp', pkg: ['barback']);
-
+     pubGet();
      pubServe();
      requestShouldSucceed("foo.out", "primary: true, secondary: false");
      endPubServe();