Tests for exceptional situations in MemoryResourceProvider.

pkg/analysis_server/lib/src/resource.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 resource;
 
 import 'dart:io' as io;
 
 import 'package:analyzer/src/generated/engine.dart' show TimestampedData;
 import 'package:analyzer/src/generated/java_io.dart';
@@ skipping 229 matching lines @@
     path = posix.normalize(path);
     Resource resource = _pathToResource[path];
     if (resource == null) {
       resource = new _MemoryFile(this, path);
     }
     return resource;
   }
 
   Folder newFolder(String path) {
     path = posix.normalize(path);
-    if (path.isEmpty) {
-      throw new ArgumentError('Empty paths are not supported');
-    }
     if (!path.startsWith('/')) {
       throw new ArgumentError("Path must start with '/'");
     }
     _MemoryFolder folder = null;
     String partialPath = "";
     for (String pathPart in path.split('/')) {
       if (pathPart.isEmpty) {
         continue;
       }
       partialPath += '/' + pathPart;
@@ skipping 109 matching lines @@
   Resource getResource(String path) {
     if (io.FileSystemEntity.isDirectorySync(path)) {
       io.Directory directory = new io.Directory(path);
       return new _PhysicalFolder(directory);
     } else {
       io.File file = new io.File(path);
       return new _PhysicalFile(file);
     }
   }
 }