code: def test_get_set_checkpoint_storage(self):
      self.assertIsNone(
          self.checkpoint_config.get_checkpoint_storage(),
          "Default checkpoint storage should be None",
      )
  
      self.checkpoint_config.set_checkpoint_storage_dir(
          "file://var/checkpoints/"
      )
  
      self.assertEqual(
          self.checkpoint_config.get_checkpoint_storage().get_checkpoint_path(),
          "file://var/checkpoints",
          "Wrong checkpoints directory",
      )
  
file_path: flink/flink-python/pyflink/datastream/tests/test_check_point_config.py
imports: from pyflink.common import Duration
  from pyflink.datastream import CheckpointConfig, CheckpointingMode, ExternalizedCheckpointCleanup, StreamExecutionEnvironment
  from pyflink.java_gateway import get_gateway
  from pyflink.testing.test_case_utils import PyFlinkTestCase
label_desc: Use image node_id 13 for calling the CheckpointConfigTests obj's underlying member method code with example usage: obj.test_get_set_checkpoint_storage() without return types