class RuboCop::Cop::Corrector

def validate_buffer(buffer)
  return if buffer == source_buffer
  unless buffer.is_a?(::Parser::Source::Buffer)
    # actually this should be enforced by parser gem
    raise 'Corrector expected range source buffer to be a ' \
          "Parser::Source::Buffer, but got #{buffer.class}"
  end
  raise "Correction target buffer #{buffer.object_id} " \
        "name:#{buffer.name.inspect} " \
        "is not current #{@source_buffer.object_id} " \
        "name:#{@source_buffer.name.inspect} under investigation"
end