setup_fixtures

# File activerecord/lib/active_record/test_fixtures.rb, line 129
      def setup_fixtures(config = ActiveRecord::Base)
        if pre_loaded_fixtures && !use_transactional_tests
          raise RuntimeError, "pre_loaded_fixtures requires use_transactional_tests"
        end

        @fixture_cache = {}
        @fixture_cache_key = [self.class.fixture_table_names.dup, self.class.fixture_paths.dup, self.class.fixture_class_names.dup]
        @fixture_connection_pools = []
        @@already_loaded_fixtures ||= {}
        @connection_subscriber = nil
        @saved_pool_configs = Hash.new { |hash, key| hash[key] = {} }

        if run_in_transaction?
          # Load fixtures once and begin transaction.
          @loaded_fixtures = @@already_loaded_fixtures[@fixture_cache_key]
          unless @loaded_fixtures
            @@already_loaded_fixtures.clear
            @loaded_fixtures = @@already_loaded_fixtures[@fixture_cache_key] = load_fixtures(config)
          end

          setup_transactional_fixtures
        else
          # Load fixtures for every test.
          ActiveRecord::FixtureSet.reset_cache
          invalidate_already_loaded_fixtures
          @loaded_fixtures = load_fixtures(config)
        end
        setup_asynchronous_queries_session

        # Instantiate fixtures for every test if requested.
        instantiate_fixtures if use_instantiated_fixtures
      end