from dbengine.handlers import BaseHandler, handlers


class DummyHandler(BaseHandler):
  pass


def test_i_can_register_only_once():
  handlers.register_handler(DummyHandler())
  count = len(handlers.handlers)
  
  handlers.register_handler(DummyHandler())  # second time is skipped as the class is already registered
  assert count == len(handlers.handlers)
  
  handlers.unregister_handler(DummyHandler())  # clean the handlers list
  assert len(handlers.handlers) == count - 1