Install barback from a hosted source in all tests.

test/run/runs_a_generated_script_test.dart

Index: test/run/runs_a_generated_script_test.dart
diff --git a/test/run/runs_a_generated_script_test.dart b/test/run/runs_a_generated_script_test.dart
index 224d2376065c38c8da6f86f25a8e194575aede61..967182dea60afd2d4260c99274dcf856ded97d87 100644
--- a/test/run/runs_a_generated_script_test.dart
+++ b/test/run/runs_a_generated_script_test.dart
@@ -25,10 +25,13 @@ class DartTransformer extends Transformer {
 
 main() {
   integration('runs a script generated from scratch by a transformer', () {
+    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),
@@ -36,8 +39,7 @@ main() {
       ])])
     ]).create();
 
-    createLockFile('myapp', pkg: ['barback']);
-
+    pubGet();
     var pub = pubRun(args: ["bin/script"]);
 
     pub.stdout.expect("generated");