At the moment the default index name and the custom index name are the same in all environments. This causes updates triggered in eg. test mode to update data/indexes in the other environment as well.
A suggestion could be to add a suffix to the index name, like this:
@index_name = [options[:index_name] || self.table_name.underscore, RAILS_ENV || Rails.env].join("_")
Causing a User-model to use an index name of "users_production" in production environment and "users_test" in test environment.
Let me know what you think and I can provide a patch.