Better not mutate the given options Hash

activesupport/lib/active_support/core_ext/string/filters.rb

@@ -41,8 +41,8 @@ def squish!
   def truncate(truncate_at, options = {})
     return dup unless length > truncate_at
 
-    options[:omission] ||= '...'
-    length_with_room_for_omission = truncate_at - options[:omission].length
+    omission = options[:omission] || '...'
+    length_with_room_for_omission = truncate_at - omission.length
     stop = \
       if options[:separator]
         rindex(options[:separator], length_with_room_for_omission) || length_with_room_for_omission
@@ -50,6 +50,6 @@ def truncate(truncate_at, options = {})
         length_with_room_for_omission
       end
 
-    "#{self[0, stop]}#{options[:omission]}"
+    "#{self[0, stop]}#{omission}"
   end
 end