I'm attempting to mock some file operations. In the "real" object I have:

StreamWriter createFile( string name )
{
  return new StreamWriter( Path.Combine( _outFolder, name ), false, Encoding.UTF8 ) );
}

In the mock object I'd like to have:

StreamWriter createFile( string name )
{
  var ms = new MemoryStream();
  _files.Add( Path.Combine( _outFolder, name ), ms );
  return new StreamWriter( ms, Encoding.UTF8 ) );
}

where _files is a dictionary to store created files for later inspection.

However, when the consumer closes the StreamWriter, it also disposes the MeamoryStream... :-(

Any thoughts on how to pursue this?