new_contents: import biconfigs
  import json
  
  class TestMemoryStorage(object):
  
      def setup_class(cls):
          cls.change_count = 0
          def onchanged(config):
              cls.change_count += 1
  
          cls.config = biconfigs.BiConfigs(
              path='::memory::',
              default_value={'default':'value'},
              onchanged=onchanged
          )
          assert cls.change_count == 0
          assert json.dumps(cls.config) == '{"default": "value"}'
  
      def test_basic_update(self):
          self.config.clear()
          assert json.dumps(self.config) == '{}'
  
          self.config['item1'] = 'value'
          assert json.dumps(self.config) == '{"item1": "value"}'
  
          del(self.config['item1'])
          assert json.dumps(self.config) == '{}'
  
subject: Add memory test