docs: def finalize(self, result):
          """Stop the mongodb instance.
          """
  
          if not self._running:
              return
  
          # Clear out the env variable.
          del os.environ["TEST_MONGODB"]
          del os.environ["TEST_MONGODB_DATABASE"]
  
          # Kill the mongod process
          if sys.platform == 'darwin':
              self.process.kill()
          else:
              self.process.terminate()
          self.process.wait()
  
          # Clean out the test data.
          shutil.rmtree(self.mongodb_param['db_path'])
          self._running = False