resolve_config_for_connection

# File activerecord/lib/active_record/connection_handling.rb, line 361
      def resolve_config_for_connection(config_or_env)
        raise "Anonymous class is not allowed." unless name

        owner_name = primary_class? ? Base.name : name
        self.connection_specification_name = owner_name

        db_config = Base.configurations.resolve(config_or_env)
        [db_config, self]
      end