factories.rb

FactoryBot.define do
  # @example Build :user as 
  #   class Foo::User < ActiveType::Record[User]; end
  #
  #   FactoryBot.build(:user, :typed, as: Foo::User)
  trait :typed do
    transient do
      as { nil }
    end

    initialize_with do
      if as
        as.new(**attributes)
      else
        new(**attributes)
      end
    end
  end
end