Use frozen array constant

lib/ransack/constants.rb

@@ -27,6 +27,7 @@ module Ransack
     FALSE_VALUES = [false, 0, '0', 'f', 'F', 'false', 'FALSE'].to_set
     BOOLEAN_VALUES = TRUE_VALUES + FALSE_VALUES
 
+    S_SORTS             = %w(s sorts).freeze
     ASC_DESC            = %w(asc desc).freeze
     AND_OR              = %w(and or).freeze
     IN_NOT_IN           = %w(in not_in).freeze

lib/ransack/search.rb

@@ -36,7 +36,7 @@ module Ransack
 
     def build(params)
       collapse_multiparameter_attributes!(params).each do |key, value|
-        if ['s', 'sorts'].include?(key)
+        if Ransack::Constants::S_SORTS.include?(key)
           send("#{key}=", value)
         elsif base.attribute_method?(key)
           base.send("#{key}=", value)