code: def test_dummy_session():
      """DummySession works"""
      sesh = DummySession()
      assert sesh._session is None
      assert sesh.get_credential_options() == {}
  
imports: from unittest import mock
  import pytest
  from rasterio.session import DummySession, AWSSession, Session, OSSSession, GSSession, SwiftSession, AzureSession, parse_bool
label_desc: Use image node_id 3 for calling a global function with example usage: test_dummy_session() without return types