transactional fixtures in gem development

Can't I use transactional fixtures in gem (not Rails) development?

I added this to my spec_helper.rb:

RSpec.configure do |config|
  config.filter_run :focus => true
  config.run_all_when_everything_filtered = true
  config.filter_run_excluding :exclude => true

  config.mock_wi开发者_JAVA技巧th :rspec

  config.use_transactional_fixtures = true
end

But I get:

undefined method `use_transactional_fixtures=' for #<RSpec::Core::Configuration:0xb7313ca8> (NoMethodError)

Do I really have to take care of the database cleanup myself (maybe with another plugin), or could I simply "require" something to make transactional fixtures work?

Update

Here are my current requires:

require 'rubygems'
require 'bundler'
require 'logger'
require 'active_record'
require 'rspec'
require 'active_support'

use_transactional_fixtures RSpec support is defined in rspec-rails. You need to include that Gem or reproduce its functionalities in order to use it.

See https://github.com/rspec/rspec-rails/blob/6fa688fa38be8e5fc17beb4ab82e8c3981a9b8fd/lib/rspec/rails/fixture_support.rb#L11-16