class RuboCop::Cop::Style::Encoding

def investigate(processed_source)
  return if processed_source.buffer.source.empty?
  line_number = encoding_line_number(processed_source)
  message = offense(processed_source, line_number)
  return unless message
  range = source_range(processed_source.buffer, line_number + 1, 0)
  add_offense(nil, range, message)
end