adhere to rubocop guidelines

config/environments/test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
@@ -15,7 +17,7 @@ Rails.application.configure do
   # 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=3600',
   }
 
   # Show full error reports and disable caching.