docstr: %%px --targets doesn't change defaults
code: def test_cellpx_targets(self):
      """%%px --targets doesn't change defaults"""
      ip = get_ipython()
      rc = self.client
      view = rc.activate(rc.ids)
      assert view.targets == rc.ids
      ip.run_line_magic("pxconfig", "--verbose")
      for cell in ("pass", "1/0"):
          with capture_output(display=False) as io:
              try:
                  ip.run_cell_magic("px", "--targets all", cell)
              except ipp.RemoteError:
                  pass
          assert "engine(s): all" in io.stdout
          assert view.targets == rc.ids
  
imports: import re
  import signal
  import sys
  import time
  import pytest
  from IPython import get_ipython
  from IPython.utils.io import capture_output
  import ipyparallel
  from ipyparallel import AsyncResult
  from .clienttest import ClusterTestCase, generate_output, raises_remote
label_desc: Use image node_id 19 for calling the TestParallelMagics obj's underlying member method code with example usage: obj.test_cellpx_targets() without return types