thoughtbot--factory_bot/lib/factory_bot/attribute/dynamic.rb

module FactoryBot
  class Attribute
    # @api private
    class Dynamic < Attribute
      def initialize(name, ignored, block)
        super(name, ignored)
        @block = block
      end

      def to_proc
        block = @block

        -> {
          value = case block.arity
                  when 1, -1 then instance_exec(self, &block)
                  else instance_exec(&block)
          end
          raise SequenceAbuseError if FactoryBot::Sequence === value

          value
        }
      end
    end
  end
end