Allow ActiveRecord::Base.as_json to accept a frozen Hash

activerecord/CHANGELOG.md

+*   Allow ActiveRecord::Base#as_json to be passed a frozen Hash.
+
+    *Isaac Betesh*
+
 *   Deprecate locking records with unpersisted changes.
 
     *Marc Schütz*

activerecord/lib/active_record/serialization.rb

@@ -9,7 +9,7 @@ module Serialization
     end
 
     def serializable_hash(options = nil)
-      options = options.try(:clone) || {}
+      options = options.try(:dup) || {}
 
       options[:except] = Array(options[:except]).map(&:to_s)
       options[:except] |= Array(self.class.inheritance_column)

activerecord/test/cases/json_serialization_test.rb

@@ -101,6 +101,17 @@ def @contact.favorite_quote; "Constraints are liberating"; end
     assert_match %r{"favorite_quote":"Constraints are liberating"}, methods_json
   end
 
+  def test_uses_serializable_hash_with_frozen_hash
+    def @contact.serializable_hash(options = nil)
+      super({ only: %w(name) }.freeze)
+    end
+
+    json = @contact.to_json
+    assert_match %r{"name":"Konata Izumi"}, json
+    assert_no_match %r{awesome}, json
+    assert_no_match %r{age}, json
+  end
+
   def test_uses_serializable_hash_with_only_option
     def @contact.serializable_hash(options = nil)
       super(only: %w(name))