Cache classes and remove null cache store config.

config/environments/test.rb

@@ -48,6 +48,7 @@
   # recommended that you enable it in continuous integration systems to ensure eager
   # loading is working properly before deploying your code.
   config.eager_load = ENV['CI'].present? || ENV['EAGER_LOAD'].present?
+  config.cache_classes = ENV['CI'].present? || ENV['EAGER_LOAD'].present?
 
   # Configure public file server for tests with Cache-Control for performance.
   config.public_file_server.enabled = true
@@ -56,7 +57,6 @@
   # Show full error reports and disable caching.
   config.consider_all_requests_local       = true
   config.action_controller.perform_caching = true
-  config.cache_store = :null_store
 
   # Render exception templates for rescuable exceptions and raise for other exceptions.
   config.action_dispatch.show_exceptions = :none