ignore trailing whitespace in polymer transform test

pkg/polymer/test/transform/common.dart

 // Copyright (c) 2013, 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 polymer.test.transfom.common;
 
 import 'dart:async';
 
 import 'package:barback/barback.dart';
 import 'package:stack_trace/stack_trace.dart';
 import 'package:unittest/unittest.dart';
 
 String idToString(AssetId id) => '${id.package}|${id.path}';
 AssetId idFromString(String s) {
   int index = s.indexOf('|');
   return new AssetId(s.substring(0, index), s.substring(index + 1));
 }
 
+String _removeTrailingWhitespace(String str) =>
+    str.splitMapJoin('\n',
+        onNonMatch: (s) => s.replaceAll(new RegExp(r'\s+$'), ''));

[Jennifer Messerly, 2013/09/06 01:36:08]

Dart doesn't have a trimEnd, as far as I can tell.

+
 /**
  * A helper package provider that has files stored in memory, also wraps
  * [Barback] to simply our tests.
  */
 class TestHelper implements PackageProvider {
   /**
    * Maps from an asset string identifier of the form 'package|path' to the
    * file contents.
    */
   final Map<String, String> files;
@@ skipping 38 matching lines @@
     barback.updateSources(paths.map(idFromString));
   }
 
   Future<String> operator [](String assetString){
     return barback.getAssetById(idFromString(assetString))
         .then((asset) => asset.readAsString());
   }
 
   Future check(String assetIdString, String content) {
     return this[assetIdString].then((value) {
+      value = _removeTrailingWhitespace(value);
+      content = _removeTrailingWhitespace(content);
       expect(value, content, reason: 'Final output of $assetIdString differs.');
     });
   }
 
   Future checkAll(Map<String, String> files) {
     var futures = [];
     files.forEach((k, v) {
       futures.add(check(k, v));
     });
     return Future.wait(futures);
   }
 }
 
 testPhases(String testName, List<List<Transformer>> phases,
     Map<String, String> inputFiles, Map<String, String> expectedFiles) {
   test(testName, () {
     var helper = new TestHelper(phases, inputFiles)..run();
     return helper.checkAll(expectedFiles).then((_) => helper.tearDown());
   });
 }
 
 // TODO(jmesserly): this is .debug to workaround issue 13046.
 const SHADOW_DOM_TAG =
     '<script src="packages/shadow_dom/shadow_dom.debug.js"></script>\n';
 
 const INTEROP_TAG = '<script src="packages/browser/interop.js"></script>\n';
 
 const PKG_JS_INTEROP_TAG =
     '<script src="packages/js/dart_interop.js"></script>\n';