1 files changed, 14 insertions, 4 deletions
diff --git a/activemodel/lib/active_model/validations/confirmation.rb b/activemodel/lib/active_model/validations/confirmation.rb
index 3a3abce364..a51523912f 100644
--- a/activemodel/lib/active_model/validations/confirmation.rb
+++ b/activemodel/lib/active_model/validations/confirmation.rb
@@ -2,17 +2,27 @@ module ActiveModel
 
   module Validations
     class ConfirmationValidator < EachValidator # :nodoc:
+      def initialize(options)
+        super
+        setup!(options[:class])
+      end
+
       def validate_each(record, attribute, value)
         if (confirmed = record.send("#{attribute}_confirmation")) && (value != confirmed)
           human_attribute_name = record.class.human_attribute_name(attribute)
-          record.errors.add(:"#{attribute}_confirmation", :confirmation, options.merge(:attribute => human_attribute_name))
+          record.errors.add(:"#{attribute}_confirmation", :confirmation, options.merge(attribute: human_attribute_name))
         end
       end
 
-      def setup(klass)
-        klass.send(:attr_accessor, *attributes.map do |attribute|
+      private
+      def setup!(klass)
+        klass.send(:attr_reader, *attributes.map do |attribute|
           :"#{attribute}_confirmation" unless klass.method_defined?(:"#{attribute}_confirmation")
         end.compact)
+
+        klass.send(:attr_writer, *attributes.map do |attribute|
+          :"#{attribute}_confirmation" unless klass.method_defined?(:"#{attribute}_confirmation=")
+        end.compact)
       end
     end
 
@@ -47,7 +57,7 @@ module ActiveModel
       #   confirmation").
       #
       # There is also a list of default options supported by every validator:
-      # +:if+, +:unless+, +:on+ and +:strict+.
+      # +:if+, +:unless+, +:on+, +:allow_nil+, +:allow_blank+, and +:strict+.
       # See <tt>ActiveModel::Validation#validates</tt> for more information
       def validates_confirmation_of(*attr_names)
         validates_with ConfirmationValidator, _merge_attributes(attr_names)