code: def test_getitem(self):
      ar = self.client[:].apply_async(wait, 0.5)
      assert ar["completed"] == [None] * len(ar)
      with pytest.raises(KeyError):
          ar["foo"]
      ar.get(5)
      with pytest.raises(KeyError):
          ar["foo"]
      assert isinstance(ar["completed"], list)
      assert ar.completed == ar["completed"]
      assert all(isinstance(dt, datetime) for dt in 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 12 for calling the TestAsyncResult obj's underlying member method code with example usage: obj.test_getitem() without return types