fsact.rb

class User
  has_many :items
end

class Items
  belongs_to :user
  validates_presence_of :user_id
end

Factory.define(:user) do |u|
  u.name "foo"
end

Factory.define(:user_with_items, :parent => :user) do |u|
  u.items {|items| [items.association(:item), items.association(:item)]}
end

Factory.define(:item) do |i|
  i.color "red"
end

Factory.define(:item_with_user, :parent => :user) do |i|
  i.association(:user)
end