def find_by!(conditions = {})
      result = find_by(conditions)
      if result.nil?
        raise RecordNotFound.new("Couldn't find #{name} with '#{conditions.keys.first}'=#{conditions.values.first}")
      end
      result
    end
def find_by!(conditions = {})
      result = find_by(conditions)
      if result.nil?
        raise RecordNotFound.new("Couldn't find #{name} with '#{conditions.keys.first}'=#{conditions.values.first}")
      end
      result
    end
Like <tt>find_by</tt>, except that if no record is found, raises
 an <tt>ActiveMocker::RecordNotFound</tt> error.