Privatize unneededly protected methods in Action Mailer tests

actionmailer/test/base_test.rb

@@ -829,7 +829,7 @@ def a_callback
     assert_equal "special indeed!", mail["X-Special-Header"].to_s
   end
 
-  protected
+  private
 
     # Execute the block setting the given values and restoring old values after
     # the block is executed.

actionmailer/test/i18n_with_controller_test.rb

@@ -66,7 +66,7 @@ def test_send_mail
     end
   end
 
-  protected
+  private
 
     def with_translation(locale, data)
       I18n.backend.store_translations(locale, data)

actionmailer/test/mail_helper_test.rb

@@ -65,7 +65,7 @@ def use_cache
     end
   end
 
-  protected
+  private
 
     def mail_with_defaults(&block)
       mail(to: "test@localhost", from: "tester@example.com",