Fabrication has_many though. I can't figure out how to set this up properly. I've tried a few methods but can never get the test to pass.

brand.rb

class Brand < ActiveRecord::Base
  attr_accessible               :title,
                                :style_ids

  has_many                      :brand_styles, dependent: :destroy
  has_many                      :styles,       through: :brand_styles

  validates_presence_of         :title
  validates_presence_of         :styles
end

brand_fabricator.rb

Fabricator(:brand) do
  title "Coca Cola"
  
  # This returns the error:
  #1) Brand has a valid factory
     # Failure/Error: Fabricate(:brand).should be_valid
     # ActiveRecord::RecordInvalid:
       # Validation failed: Styles can't be blank
     # ./spec/models/brand_spec.rb:5:in `block (2 levels) in <top (required)>'
  # before_save do |brand|
  #  Fabricate(:brand_style, :brand => brand, :style => Fabricate(:style))
  # end

  #This returns the error:
  #1) Brand has a valid fabrication
     # Failure/Error: Fabricate(:brand).should be_valid
     # ActiveRecord::UnknownAttributeError:
       # unknown attribute: styles
     # ./spec/fabricators/brand_fabricator.rb:9:in `block (2 levels) in <top (required)>'
     # ./spec/models/brand_spec.rb:5:in `block (2 levels) in <top (required)>'
  before_save do |brand|
    Fabricate(:brand_style, :brand => brand, :styles => [Fabricate(:style)])
  end
end

brand_spec.rb

require 'spec_helper'

describe Brand do
  it "has a valid fabrication" do
    Fabricate(:brand).should be_valid
  end
end

brand_style.rb

class BrandStyle < ActiveRecord::Base
  attr_accessible :brand_id, 
                  :style_id

  belongs_to      :brand
  belongs_to      :style
end

brand_style_fabricator.rb

Fabricator(:brand_style) do
  brand
  style
end

style.rb

class Style < ActiveRecord::Base
  attr_accessible               :title

  has_many                      :brand_styles, dependent: :destroy
  has_many                      :brands,       through: :brand_styles

  validates_presence_of         :title
end

style_fabricator.rb

Fabricator(:style) do
  title "Beverage"
end