add tests for the Ruby backend

main-server/config/environments/test.rb

@@ -31,13 +31,7 @@ Rails.application.configure do
   # Store uploaded files on the local file system in a temporary directory.
   config.active_storage.service = :test
 
-  # 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
-
-  # Set host to be used by links generated in mailer templates.
-  config.action_mailer.default_url_options = { host: "example.com" }
+  # Action Mailer is not enabled in this application.
 
   # Print deprecation notices to the stderr.
   config.active_support.deprecation = :stderr