Keep all methods in object/deep_dup

activesupport/lib/active_support/core_ext/array.rb

 require 'active_support/core_ext/array/wrap'
 require 'active_support/core_ext/array/access'
 require 'active_support/core_ext/array/uniq_by'
-require 'active_support/core_ext/array/deep_dup'
 require 'active_support/core_ext/array/conversions'
 require 'active_support/core_ext/array/extract_options'
 require 'active_support/core_ext/array/grouping'

activesupport/lib/active_support/core_ext/array/deep_dup.rb

-class Array
-  # Returns a deep copy of array.
-  def deep_dup
-    map { |it| it.deep_dup }
-  end
-end

activesupport/lib/active_support/core_ext/hash.rb

 require 'active_support/core_ext/hash/conversions'
 require 'active_support/core_ext/hash/deep_merge'
-require 'active_support/core_ext/hash/deep_dup'
 require 'active_support/core_ext/hash/diff'
 require 'active_support/core_ext/hash/except'
 require 'active_support/core_ext/hash/indifferent_access'

activesupport/lib/active_support/core_ext/hash/deep_dup.rb

-class Hash
-  # Returns a deep copy of hash.
-  def deep_dup
-    each_with_object(dup) do |(key, value), hash|
-      hash[key.deep_dup] = value.deep_dup
-    end
-  end
-end

activesupport/lib/active_support/core_ext/object/deep_dup.rb

@@ -4,3 +4,19 @@ def deep_dup
     duplicable? ? dup : self
   end
 end
+
+class Array
+  # Returns a deep copy of array.
+  def deep_dup
+    map { |it| it.deep_dup }
+  end
+end
+
+class Hash
+  # Returns a deep copy of hash.
+  def deep_dup
+    each_with_object(dup) do |(key, value), hash|
+      hash[key.deep_dup] = value.deep_dup
+    end
+  end
+end

activesupport/test/core_ext/deep_dup_test.rb

+require 'abstract_unit'
 require 'active_support/core_ext/object'
-require 'active_support/core_ext/array'
-require 'active_support/core_ext/hash'
 
 class DeepDupTest < ActiveSupport::TestCase