ActiveSupport::BufferedLogger can be subclassed

activesupport/lib/active_support/buffered_logger.rb

@@ -2,6 +2,10 @@ require 'active_support/deprecation'
 require 'active_support/logger'
 
 module ActiveSupport
-  BufferedLogger = ActiveSupport::Deprecation::DeprecatedConstantProxy.new(
-    'BufferedLogger', '::ActiveSupport::Logger')
+  class BufferedLogger < Logger
+    def self.inherited(*)
+      ::ActiveSupport::Deprecation.warn 'ActiveSupport::BufferedLogger is deprecated! Use ActiveSupport::Logger instead.'
+      super
+    end
+  end
 end

activesupport/test/deprecation/buffered_logger_test.rb

@@ -0,0 +1,14 @@
+require 'abstract_unit'
+require 'active_support/buffered_logger'
+
+class BufferedLoggerTest < ActiveSupport::TestCase
+
+  def test_can_be_subclassed
+    warn = 'ActiveSupport::BufferedLogger is deprecated! Use ActiveSupport::Logger instead.'
+
+    ActiveSupport::Deprecation.expects(:warn).with(warn).once
+
+    Class.new(ActiveSupport::BufferedLogger)
+  end
+
+end