Add File.renameSync() to virtual file system.

pkg/analyzer/lib/file_system/memory_file_system.dart

Index: pkg/analyzer/lib/file_system/memory_file_system.dart
diff --git a/pkg/analyzer/lib/file_system/memory_file_system.dart b/pkg/analyzer/lib/file_system/memory_file_system.dart
index d3ec74f11019eab7cb5860dc94258c8de1661664..b15b256b2e239657c029a96fff0a2aaa28a19348 100644
--- a/pkg/analyzer/lib/file_system/memory_file_system.dart
+++ b/pkg/analyzer/lib/file_system/memory_file_system.dart
@@ -159,6 +159,21 @@ class MemoryResourceProvider implements ResourceProvider {
     }
   }
 
+  void renameFileSync(String path, String newPath) {
+    if (newPath == path) {
+      return;
+    }
+    if (_pathToResource[newPath] is _MemoryFolder) {
+      throw new FileSystemException(
+          path, 'Could not be renamed: $newPath is a folder.');
+    }
+    _pathToResource.remove(path);
+    _pathToContent[newPath] = _pathToContent.remove(path);
+    _pathToBytes[newPath] = _pathToBytes.remove(path);
+    _pathToTimestamp[newPath] = _pathToTimestamp.remove(path);
+    _pathToWatchers[newPath] = _pathToWatchers.remove(path);

[Brian Wilkerson, 2016/03/17 19:31:00]

Does this need to call _notifyWatchers?

+  }
+
   File updateFile(String path, String content, [int stamp]) {
     path = pathContext.normalize(path);
     newFolder(pathContext.dirname(path));
@@ -214,7 +229,9 @@ class MemoryResourceProvider implements ResourceProvider {
     });
   }
 
-  void _setFileBytes(String path, List<int> bytes) {
+  void _setFileBytes(_MemoryFile file, List<int> bytes) {
+    String path = file.path;
+    _pathToResource[path] = file;
     _pathToBytes[path] = bytes;
     _pathToTimestamp[path] = nextStamp++;
     _notifyWatchers(path, ChangeType.MODIFY);
@@ -271,6 +288,11 @@ class _MemoryDummyLink extends _MemoryResource implements File {
   }
 
   @override
+  Resource renameSync(String newPath) {
+    throw new FileSystemException(path, 'File could not be renamed');
+  }
+
+  @override
   void writeAsBytesSync(List<int> bytes) {
     throw new FileSystemException(path, 'File could not be written');
   }
@@ -335,8 +357,14 @@ class _MemoryFile extends _MemoryResource implements File {
   }
 
   @override
+  File renameSync(String newPath) {
+    _provider.renameFileSync(path, newPath);
+    return _provider._newFile(newPath);
+  }
+
+  @override
   void writeAsBytesSync(List<int> bytes) {
-    _provider._setFileBytes(path, bytes);
+    _provider._setFileBytes(this, bytes);
   }
 }