code: def test_single_result(self):
      ar = self.client[-1].apply_async(wait, 0.5)
      with pytest.raises(KeyError):
          ar["foo"]
      assert ar["completed"] is None
      assert ar.get(5) == 0.5
      assert isinstance(ar["completed"], datetime)
      assert isinstance(ar.completed, datetime)
      assert ar.completed == ar["completed"]
  
imports: import os
  import time
  from datetime import datetime
  import pytest
  from IPython.utils.io import capture_output
  import ipyparallel
  from ipyparallel import error
  from .clienttest import ClusterTestCase, raises_remote
label_desc: Use image node_id 13 for calling the TestAsyncResult obj's underlying member method code with example usage: obj.test_single_result() without return types