What can I do for model testing in Unit/Test on ruby

rubyonrails-talk
1

For model testing in Unit/test on ruby, I just test the DB saving of all the tables? Like this model def self.get_latest_answers_for_person(person_id, limit=10)     return nil if person_id.nil?     return Answer.find_by_sql(['       SELECT * FROM answers       WHERE person_id = ?       ORDER BY created_at DESC       LIMIT ?;       ', person_id, limit])   end I just test data in answer and users tables saving? Help!