--- a/config/environments/test.rb	Fri May 31 09:45:02 2019 +0900
+++ b/config/environments/test.rb	Sun Jul 14 15:38:04 2019 +0900
@@ -1,10 +1,11 @@
+# The test environment is used exclusively to run your application's
+# test suite. You never need to work with it otherwise. Remember that
+# your test database is "scratch space" for the test suite and is wiped
+# and recreated between test runs. Don't rely on the data there!
+
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
-  # The test environment is used exclusively to run your application's
-  # test suite. You never need to work with it otherwise. Remember that
-  # your test database is "scratch space" for the test suite and is wiped
-  # and recreated between test runs. Don't rely on the data there!
   config.cache_classes = true
 
   # Do not eager load code on boot. This avoids loading your whole application
@@ -15,28 +16,23 @@
   # Configure public file server for tests with Cache-Control for performance.
   config.public_file_server.enabled = true
   config.public_file_server.headers = {
-    "Cache-Control" => "public, max-age=3600"
+    'Cache-Control' => "public, max-age=#{1.hour.to_i}"
   }
 
   # Show full error reports and disable caching.
   config.consider_all_requests_local       = true
   config.action_controller.perform_caching = false
+  config.cache_store = :null_store
 
   # Raise exceptions instead of rendering exception templates.
   config.action_dispatch.show_exceptions = false
 
   # Disable request forgery protection in test environment.
   config.action_controller.allow_forgery_protection = false
-  # config.action_mailer.perform_caching = false
-
-  # Tell Action Mailer not to deliver emails to the real world.
-  # The :test delivery method accumulates sent emails in the
-  # ActionMailer::Base.deliveries array.
-  # config.action_mailer.delivery_method = :test
 
   # Print deprecation notices to the stderr.
   config.active_support.deprecation = :stderr
 
-  # Raises error for missing translations
+  # Raises error for missing translations.
   # config.action_view.raise_on_missing_translations = true
 end