diff --git a/railties/test/isolation/abstract_unit.rb b/railties/test/isolation/abstract_unit.rb
index <HASH>..<HASH> 100644
--- a/railties/test/isolation/abstract_unit.rb
+++ b/railties/test/isolation/abstract_unit.rb
@@ -297,6 +297,8 @@ class ActiveSupport::TestCase
   include TestHelpers::Rack
   include TestHelpers::Generation
 
+  self.test_order = :sorted
+
   private
 
   def capture(stream)
Set test order in ActiveSupport::TestCase of isolation/abstract_unit