root/trunk/activerecord/test/models/category.rb

class Category < ActiveRecord::Base
  has_and_belongs_to_many :posts
  has_and_belongs_to_many :special_posts, :class_name => "Post"
  has_and_belongs_to_many :other_posts, :class_name => "Post"

  has_and_belongs_to_many(:select_testing_posts,
                          :class_name => 'Post',
                          :foreign_key => 'category_id',
                          :association_foreign_key => 'post_id',
                          :select => 'posts.*, 1 as correctness_marker')

  has_and_belongs_to_many :post_with_conditions,
                          :class_name => 'Post',
                          :conditions => { :title => 'Yet Another Testing Title' }
  def self.what_are_you
    'a category...'
  end

  has_many :categorizations
  has_many :authors, :through => :categorizations, :select => 'authors.*, categorizations.post_id'
end

class SpecialCategory < Category

  def self.what_are_you
    'a special category...'
  end

end