MongoDB.GridFS.GridFile.Delete C# (CSharp) Метод

        public void Delete(Document query )
        {
            foreach(Document doc in ListFiles(query).Documents){
                Delete((Oid)doc["_id"]);
            }
        }

 public void TestDeleteRemovesChunks(){
     Object id;
     string filename = "deletebyname.txt";
     string fs = "fs";
     GridFile gf = new GridFile(DB,fs);
     using(GridFileStream gfs = gf.Create(filename, FileMode.CreateNew)){
         id = gfs.GridFileInfo.Id;
         TextWriter tw = new StreamWriter(gfs);
         tw.WriteLine("test");
         tw.Close();
     }
     Assert.AreEqual(1, CountChunks(fs, id), "Chunks not found");
     gf.Delete("deletebyname.txt");
     Assert.AreEqual(0, CountChunks(fs, id), "Chunks found");
 }