switch package to strong mode

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.
 @TestOn('vm')
 library code_transformers.test.assets_test;
 
 import 'dart:async';
 
 import 'package:barback/barback.dart';
 import 'package:code_transformers/assets.dart';
 import 'package:transformer_test/utils.dart';
 import 'package:test/test.dart';
 
 main() {
   group('uriToAssetId', uriToAssetIdTests);
   group('assetIdToUri', assetIdToUriTests);
 }
 
 void assetIdToUriTests() {
   void testAssetIdToUri(String name, AssetId assetId,
       {String result, AssetId from, String message}) {
     test(name, () {
       var transformer = new Validator((transform) {
         var uriOut = assetIdToUri(assetId,
             logger: transform.logger, span: null, from: from);
         expect(uriOut, result);
       });
-      var messages = [];
+      var messages = <String>[];
       if (message != null) messages.add(message);
 
       return applyTransformers([[transformer]],
           inputs: {assetId.toString(): ''}, messages: messages);
     });
   }
 
   testAssetIdToUri('resolves relative URIs', new AssetId('a', 'web/main.dart'),
       result: 'main.dart', from: new AssetId('a', 'web/foo.dart'));
 
@@ skipping 30 matching lines @@
 
 void uriToAssetIdTests() {
   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 = [];
+      var messages = <String>[];
       if (message != null) messages.add(message);
 
       return applyTransformers([[transformer]],
           inputs: {source.toString(): ''}, messages: messages);
     });
   }
 
   testAssetUri('resolves relative URIs',
       source: new AssetId('a', 'web/main.dart'),
       uri: 'foo.dart',
@@ skipping 51 matching lines @@
 
 class Validator extends Transformer {
   final Function validation;
 
   Validator(this.validation);
 
   Future apply(Transform transform) {
     return new Future.value(validation(transform));
   }
 }