Merge pull request #8518 from rwz/inheritable-basic-object

Properly deprecate AS::BasicObject without breaking subclasses of it

activesupport/lib/active_support/basic_object.rb

 require 'active_support/deprecation'
+require 'active_support/proxy_object'
 
 module ActiveSupport
   # :nodoc:
-  # Deprecated in favor of ActiveSupport::ProxyObject
-  BasicObject = Deprecation::DeprecatedConstantProxy.new('ActiveSupport::BasicObject', 'ActiveSupport::ProxyObject')
+  class BasicObject < ProxyObject
+    def self.inherited(*)
+      ::ActiveSupport::Deprecation.warn 'ActiveSupport::BasicObject is deprecated! Use ActiveSupport::ProxyObject instead.'
+      super
+    end
+  end
 end

activesupport/test/deprecation/basic_object_test.rb

+require 'abstract_unit'
+require 'active_support/deprecation'
+require 'active_support/basic_object'
+
+
+class BasicObjectTest < ActiveSupport::TestCase
+  test 'BasicObject warns about deprecation when inherited from' do
+    warn = 'ActiveSupport::BasicObject is deprecated! Use ActiveSupport::ProxyObject instead.'
+    ActiveSupport::Deprecation.expects(:warn).with(warn).once
+    Class.new(ActiveSupport::BasicObject)
+  end
+end
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