Install barback from a hosted source in all tests.

test/run/does_not_run_on_transformer_error_test.dart

Index: test/run/does_not_run_on_transformer_error_test.dart
diff --git a/test/run/does_not_run_on_transformer_error_test.dart b/test/run/does_not_run_on_transformer_error_test.dart
index 0372b3465cbbaf9cb803168b7ab5671c05fb60df..154656c32de6cf646e3646a120b204071bcc5192 100644
--- a/test/run/does_not_run_on_transformer_error_test.dart
+++ b/test/run/does_not_run_on_transformer_error_test.dart
@@ -31,10 +31,13 @@ class FailingTransformer extends Transformer {
 
 main() {
    integration('does not run if a transformer has an error', () {
+     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", [
@@ -46,8 +49,7 @@ main() {
        ])
      ]).create();
 
-     createLockFile('myapp', pkg: ['barback']);
-
+     pubGet();
      var pub = pubRun(args: ["bin/script"]);
 
      pub.stderr.expect("[Error from Failing]:");