Use the new test runner.

test/run/mode_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 
 const TRANSFORMER = """
 import 'dart:async';
 
 import 'package:barback/barback.dart';
 
 class DartTransformer extends Transformer {
   final BarbackSettings _settings;
 
   DartTransformer.asPlugin(this._settings);
 
   String get allowedExtensions => '.in';
 
   void apply(Transform transform) {
     transform.addOutput(new Asset.fromString(
         new AssetId(transform.primaryInput.id.package, "bin/script.dart"),
         "void main() => print('\${_settings.mode.name}');"));
   }
 }
 """;
 
 main() {
-  initConfig();
   withBarbackVersions("any", () {
     integration('runs a local script with customizable modes', () {
       d.dir(appPath, [
         d.pubspec({
           "name": "myapp",
           "transformers": ["myapp/src/transformer"]
         }),
         d.dir("lib", [d.dir("src", [
           d.file("transformer.dart", TRANSFORMER),
           d.file("primary.in", "")
@@ skipping 35 matching lines @@
       pub.stdout.expect("release");
       pub.shouldExit();
 
       // A custom mode should be specifiable.
       pub = pubRun(args: ["--mode", "custom-mode", "foo:script"]);
       pub.stdout.expect("custom-mode");
       pub.shouldExit();
     });
   });
 }