module ThoughtBot::Shoulda::ActiveRecord::Macros

def should_have_one(*associations)
  dependent = get_options!(associations, :dependent)
  klass = model_class
  associations.each do |association|
    name = "have one #{association}"
    name += " dependent => #{dependent}" if dependent
    should name do
      reflection = klass.reflect_on_association(association)
      assert reflection, "#{klass.name} does not have any relationship to #{association}"
      assert_equal :has_one, reflection.macro
      associated_klass = (reflection.options[:class_name] || association.to_s.camelize).constantize
      if reflection.options[:foreign_key]
        fk = reflection.options[:foreign_key]
      elsif reflection.options[:as]
        fk = reflection.options[:as].to_s.foreign_key
        fk_type = fk.gsub(/_id$/, '_type')
        assert associated_klass.column_names.include?(fk_type),
               "#{associated_klass.name} does not have a #{fk_type} column."
      else
        fk = klass.name.foreign_key
      end
      assert associated_klass.column_names.include?(fk.to_s),
             "#{associated_klass.name} does not have a #{fk} foreign key."
      if dependent
        assert_equal dependent.to_s,
                     reflection.options[:dependent].to_s,
                     "#{association} should have #{dependent} dependency"
      end
    end
  end
end