zammad/spec/factories/activity_stream.rb

FactoryBot.define do
  factory :activity_stream do
    transient do
      o { Ticket.first }
    end

    association :type, factory: :type_lookup
    activity_stream_object_id { ObjectLookup.by_name(o.class.name) }
    o_id                      { o.id }
    created_by_id             { 1 }
  end
end