validates limit_by node

lib/arel/nodes/limit_by.rb

@@ -4,9 +4,18 @@ class LimitBy < Arel::Nodes::Unary
       attr_reader :column
 
       def initialize(limit, column)
-        @column = column
+        raise ArgumentError, 'Limit should be an integer' unless limit.is_a?(Integer)
+        raise ArgumentError, 'Limit should be a positive integer' unless limit >= 0
+        raise ArgumentError, 'Column should be a Symbol or String' unless column.is_a?(String) || column.is_a?(Symbol)
+
         super(limit)
       end
+
+      private
+
+      def sanitize(value)
+        value 
+      end
     end
   end
 end