app:update

config/environments/test.rb

@@ -34,6 +34,8 @@ Rails.application.configure do
   # Store uploaded files on the local file system in a temporary directory.
   config.active_storage.service = :test
 
+  # Disable caching for Action Mailer templates even if Action Controller
+  # caching is enabled.
   config.action_mailer.perform_caching = false
 
   # Tell Action Mailer not to deliver emails to the real world.