Какова лучшая практика для установки связей с factory_girl в огурце?

You can define multiple associations in a factory.
Like the following :

Factory.define :item do |item|
    item.name          "item_name"
end

Factory.define :group do |group|
    group.name          "group_name"
    group.items         { |items| [ items.association(:item), items.association(:item) ] }
end

Doing a Factory(:group) will create your group uplet with two items in it.