pkg/code_transformers: removed unused imports, require latest unittest

pkg/code_transformers/test/assets_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.
 
 library code_transformers.test.assets_test;
 
 import 'dart:async';
-import 'dart:io' show File, Platform;
 
 import 'package:barback/barback.dart';
 import 'package:code_transformers/assets.dart';
-import 'package:code_transformers/resolver.dart';
 import 'package:code_transformers/tests.dart';
-import 'package:path/path.dart' as path;
 import 'package:unittest/compact_vm_config.dart';
 import 'package:unittest/unittest.dart';
 
 main() {
   useCompactVMConfiguration();
 
 
-  Future testAssetUri(String name,
+  void testAssetUri(String name,
       {AssetId source, String uri, AssetId result, String message,
       bool errorOnAbsolute: true}) {
     test(name, () {
       var transformer = new Validator((transform) {
       var assetId = uriToAssetId(source, uri, transform.logger, null,
           errorOnAbsolute: errorOnAbsolute);
         expect(assetId, result);
       });
       var messages = [];
       if (message != null) messages.add(message);
@@ skipping 68 matching lines @@
   final Function validation;
 
   Validator(this.validation);
 
   Future<bool> isPrimary(Asset input) => new Future.value(true);
 
   Future apply(Transform transform) {
     return new Future.value(validation(transform));
   }
 }