class ActiveModel::Validations::ComparisonValidator

def check_validity!
  unless (options.keys & COMPARE_CHECKS.keys).any?
    raise ArgumentError, "Expected one of :greater_than, :greater_than_or_equal_to, "\
    ":equal_to, :less_than, :less_than_or_equal_to, or :other_than option to be supplied."
  end
end