Merge pull request rails#51638 from Earlopain/deprecate-as-proxy-object

Deprecate `ActiveSupport::ProxyObject`

Author: rafaelfranca

activesupport/CHANGELOG.md

@@ -1,3 +1,7 @@
+*   Deprecate `ActiveSupport::ProxyObject` in favor of Ruby's buildin `BasicObject`
+
+    *Earlopain*
+
 *   `stub_const` now accepts a `exists: false` parameter to allow stubbing missing constants.
 
     *Jean Boussier*

activesupport/lib/active_support/proxy_object.rb

@@ -1,17 +1,20 @@
 # frozen_string_literal: true
 
 module ActiveSupport
-  # = Active Support Proxy \Object
-  #
-  # A class with no predefined methods that behaves similarly to Ruby's
-  # BasicObject. Used for proxy classes.
-  class ProxyObject < ::BasicObject
+  class ProxyObject < ::BasicObject # :nodoc:
     undef_method :==
     undef_method :equal?
 
     # Let ActiveSupport::ProxyObject at least raise exceptions.
     def raise(*args)
       ::Object.send(:raise, *args)
     end
+
+    def self.inherited(_subclass)
+      ::ActiveSupport.deprecator.warn(<<~MSG)
+        ActiveSupport::ProxyObject is deprecated and will be removed in Rails 7.3.
+        Use Ruby's buildin BasicObject instead.
+      MSG
+    end
   end
 end

activesupport/test/proxy_object_test.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+require_relative "abstract_unit"
+
+class ProxyObjectTest < ActiveSupport::TestCase
+  def test_accessing_proxy_object_is_deprecated
+    proxy = assert_deprecated(ActiveSupport.deprecator) do
+      Class.new(ActiveSupport::ProxyObject) do
+        def some_method
+          "foo"
+        end
+      end
+    end
+    assert_equal("foo", proxy.new.some_method)
+  end
+end