FactoryGirl issues with attributes_for

character.rb

class Character < ActiveRecord::Base
  belongs_to :player, :inverse_of => :characters, :touch => true
  belongs_to :archetype, :inverse_of => :characters, :touch => true

  validates_presence_of :name
  validates_presence_of :player, :archetype, :char_type, :on => :update

  validates_uniqueness_of :name
  validates_format_of :char_type, :with => /g|m|r/ # General Alt, Main, Raid Alt
end

characters.rb

FactoryGirl.define do
  sequence :character_name do |n|
    "Character #{n}"
  end

  factory :character do |f|
    f.player  { |a| a.association(:player) }
    f.name { generate(:character_name) }
    f.char_type 'g'
    f.archetype { |a| a.association(:archetype) }
  end

  factory :invalid_character, parent: :character do |f|
    f.player nil
    f.name nil
    f.char_type 'f'
  end
end

characters_controller_spec.rb

require 'spec_helper'

describe CharactersController do
  fixtures :users

  before(:each) do
    login_as :foo
  end

  describe 'POST #create' do
    context 'with valid attributes' do
      it 'saves the new character' do
        expect {
          post :create, character: FactoryGirl.attributes_for(:character)
        }.to change(Character, :count).by(1)
      end

      it 'redirects to the new character' do
        post :create, character: FactoryGirl.attributes_for(:character)
        response.should redirect_to Character.last
      end
    end

    context 'with invalid attributes' do
      it 'does not save the new character' do
        expect {
          post :create, character: FactoryGirl.attributes_for(:invalid_character)
        }.to_not change(Character, :count)
      end

      it 're-renders the :new template' do
        post :create, character: FactoryGirl.attributes_for(:invalid_character)
        response.should render_template :new
      end
    end
  end
end

instance.rb

class Instance < ActiveRecord::Base
  belongs_to :raid, inverse_of: :instances, touch: true
  belongs_to :zone, inverse_of: :instances, touch: true

  has_many :drops, :inverse_of => :instance, dependent: :destroy
  has_many :character_instances, :inverse_of => :instance, dependent: :destroy

  has_many :kills, :through => :drops, :source => :mob, :uniq => true
  has_many :characters, :through => :character_instances
  has_many :players, :through => :characters, :uniq => true

  accepts_nested_attributes_for :character_instances, :reject_if => :all_blank, :allow_destroy => true
  accepts_nested_attributes_for :drops, :reject_if => :all_blank, :allow_destroy => true

  validates_presence_of :raid, :zone, :start_time
  validates_uniqueness_of :start_time, :scope => [:raid_id, :zone_id]
end

instances.rb

FactoryGirl.define do
  sequence :start_time do |n|
    n.hours
  end

  factory :instance do |f|
    raid_date = Date.parse('01/01/2012')
    f.raid { |a| a.association(:raid, raid_date: raid_date) }
    f.zone { |a| a.association(:zone) }
    f.start_time { raid_date + generate(:start_time) }
  end

  factory :invalid_instance, parent: :instance do |f|
    f.raid nil
    f.zone nil
    f.start_time nil
  end
end

instances_controller_spec.rb

require 'spec_helper'

describe InstancesController do
  fixtures :users

  before(:each) do
    login_as :foo
  end

  describe 'POST #create' do
    context 'with valid attributes' do
      it 'saves the new instance' do
        expect {
          post :create, instance: FactoryGirl.build(:instance).attributes.symbolize_keys
        }.to change(Instance, :count).by(1)
      end

      it 'redirects to the new instance' do
        post :create, instance: FactoryGirl.build(:instance).attributes.symbolize_keys
        response.should redirect_to Instance.last
      end
    end

    context 'with invalid attributes' do
      it 'does not save the new instance' do
        expect {
          post :create, instance: FactoryGirl.attributes_for(:invalid_instance)
        }.to_not change(Instance, :count)
      end

      it 're-renders the :new template' do
        post :create, instance: FactoryGirl.attributes_for(:invalid_instance)
        response.should render_template :new
      end
    end
  end
end

The characters factory returns valid association attributes when FactoryGirl.attributes_for(:character) is called.
The instances factory returns null attributes when the above is done, but using FactoryGirl.build(:instance).symbolize_keys does work.