private static ArraySegment <byte> StringToUtf8BufferWithEmptySpace(string testString, int emptySpaceSize = 2048) { var utf8Bytes = new Utf8Span(testString).Bytes; var buffer = new byte[utf8Bytes.Length + emptySpaceSize]; utf8Bytes.CopyTo(buffer); return(new ArraySegment <byte>(buffer, 0, utf8Bytes.Length)); }