Install barback from a hosted source in all tests.

test/transformer/fails_to_load_an_unconfigurable_transformer_when_config_is_passed_test.dart

Index: test/transformer/fails_to_load_an_unconfigurable_transformer_when_config_is_passed_test.dart
diff --git a/test/transformer/fails_to_load_an_unconfigurable_transformer_when_config_is_passed_test.dart b/test/transformer/fails_to_load_an_unconfigurable_transformer_when_config_is_passed_test.dart
index 1c2c66ed700af1dc0cc60b1345b8664149a3661a..7565996f249a03b98d61e9ca2ca6be1c036dff5b 100644
--- a/test/transformer/fails_to_load_an_unconfigurable_transformer_when_config_is_passed_test.dart
+++ b/test/transformer/fails_to_load_an_unconfigurable_transformer_when_config_is_passed_test.dart
@@ -13,18 +13,20 @@ import '../serve/utils.dart';
 main() {
    integration("fails to load an unconfigurable transformer when config is "
        "passed", () {
+     serveBarback();
+
      d.dir(appPath, [
        d.pubspec({
          "name": "myapp",
-         "transformers": [{"myapp/src/transformer": {'foo': 'bar'}}]
+         "transformers": [{"myapp/src/transformer": {'foo': 'bar'}}],
+         "dependencies": {"barback": "any"}
        }),
        d.dir("lib", [d.dir("src", [
          d.file("transformer.dart", REWRITE_TRANSFORMER)
        ])])
      ]).create();
 
-     createLockFile('myapp', pkg: ['barback']);
-
+     pubGet();
      var pub = startPubServe();
      pub.stderr.expect(startsWith('No transformers that accept configuration '
          'were defined in '));