setup_shared_connection_pool

# File activerecord/lib/active_record/test_fixtures.rb, line 218
      def setup_shared_connection_pool
        handler = ActiveRecord::Base.connection_handler

        handler.connection_pool_names.each do |name|
          pool_manager = handler.send(:connection_name_to_pool_manager)[name]
          pool_manager.shard_names.each do |shard_name|
            writing_pool_config = pool_manager.get_pool_config(ActiveRecord.writing_role, shard_name)
            @saved_pool_configs[name][shard_name] ||= {}
            pool_manager.role_names.each do |role|
              next unless pool_config = pool_manager.get_pool_config(role, shard_name)
              next if pool_config == writing_pool_config

              @saved_pool_configs[name][shard_name][role] = pool_config
              pool_manager.set_pool_config(role, shard_name, writing_pool_config)
            end
          end
        end
      end