Fix for 'Create part' Quick Fix.

pkg/analyzer/test/src/context/context_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 test.src.context.context_test;
 
 import 'dart:async';
 
 import 'package:analyzer/src/cancelable_future.dart';
 import 'package:analyzer/src/context/cache.dart';
@@ skipping 17 matching lines @@
         ChangeSet,
         IncrementalAnalysisCache,
         TimestampedData;
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/html.dart' as ht;
 import 'package:analyzer/src/generated/java_engine.dart';
 import 'package:analyzer/src/generated/resolver.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/task/dart.dart';
+import 'package:path/path.dart' as pathos;
 import 'package:unittest/unittest.dart';
 import 'package:watcher/src/utils.dart';
 
 import '../../generated/engine_test.dart';
 import '../../generated/test_support.dart';
 import '../../reflective_tests.dart';
 import 'abstract_context.dart';
 
 main() {
   groupSep = ' | ';
@@ skipping 2071 matching lines @@
 class _AnalysisContextImplTest_test_applyChanges_removeContainer
     implements SourceContainer {
   Source libB;
   _AnalysisContextImplTest_test_applyChanges_removeContainer(this.libB);
   @override
   bool contains(Source source) => source == libB;
 }
 
 class _Source_getContent_throwException extends NonExistingSource {
   _Source_getContent_throwException(String name)
-      : super(name, UriKind.FILE_URI);
+      : super(name, pathos.toUri(name), UriKind.FILE_URI);
 
   @override
   TimestampedData<String> get contents {
     throw 'Read error';
   }
 
   @override
   bool exists() => true;
 }