How to move document from folder to same Document Library using workflow

Let consider Folder name TestDoc and here i am coping a file from source folder FolderA(or from any where in the TestDoc library) to destination folder FolderB

see code below.

public override void ItemUpdated(SPItemEventProperties properties)
{
    string strItemProperty = properties.ListTitle.ToString();
    if (strItemProperty == "TestDoc")
    {
    SPListItem sourceItem = properties.ListItem;
    SPFolder dFolder = sourceItem.Web.Folders[sourceItem.Web.Url + "/TestDoc/"];
    SPFile sfile = sourceItem.File;
    Stream fileStream = null;
    if (sfile != null)
    {
        fileStream = sfile.OpenBinaryStream();
        dFolder.Files.Add(sourceItem.Web.Url + "/TestDoc/FolderB/" + sourceItem.File.Name, fileStream);
        fileStream.Close();
    }
    }
base.ItemUpdated(properties);
}