class RuboCop::OptionsValidator

def validate_cop_list(names)

called from within Options.
Cop name validation must be done later than option parsing, so it's not 
def validate_cop_list(names)
  return unless names
  cop_names = Cop::Registry.global.names
  departments = Cop::Registry.global.departments.map(&:to_s)
  names.each do |name|
    next if cop_names.include?(name)
    next if departments.include?(name)
    next if SYNTAX_DEPARTMENTS.include?(name)
    raise IncorrectCopNameError, format_message_from(name, cop_names)
  end
end