title: How can I build/create a many-to-many association in factory_girl?
body: <p>I have a <code>Person</code> model that has a many-to-many relationship with an <code>Email</code> model and I want to create a factory that lets me generate a first and last name for the person (this is already done) and create an email address that is based off of that person's name. Here is what I have for create a <code>person</code>'s name:</p>
  
  <pre><code>Factory.sequence :first_name do |n|
    first_name = %w[FirstName1 FirstName2] # ... etc (I'm using a real subset of first names)
    first_name[(rand * first_name.length)]
  end
  
  Factory.sequence :last_name do |n|
    last_name = %w[LastName1 LastName2] # ... etc (I'm using a real subset of last names)
    last_name[(rand * last_name.length)]
  end
  
  Factory.define :person do |p|
    #p.id ???
    p.first_name { Factory.next(:first_name) }
    p.last_name { Factory.next(:last_name) }
    #ok here is where I'm stuck
    #p.email_addresses {|p| Factory(:email_address_person_link) }
  end
  
  Factory.define :email_address_person_link do |eapl|
    # how can I link this with :person and :email_address ? 
    # eapl.person_id ???
    # eapl.email_address_id ???
  end
  
  Factory.define :email_address do |e|
    #how can I pass p.first_name and p.last_name into here?
    #e.id ???
    e.email first_name + "." + last_name + "@test.com"
  end
  </code></pre>