code: def test_signal_handling(self):
      x = DummySaveable()
  
      # Increment the value of DummySavable.
      x.state["state"].assign_add(1)
  
      directory = self.get_tempdir()
  
      # Patch signals.add_handler so the registered signal handler sets the event.
      with mock.patch.object(
          launchpad, "register_stop_handler"
      ) as mock_register_stop_handler:
  
          def add_handler(fn):
              fn()
  
          mock_register_stop_handler.side_effect = add_handler
  
          runner = tf2_savers.CheckpointingRunner(
              wrapped=x, time_delta_minutes=0, directory=directory
          )
          with self.assertRaises(SystemExit):
              runner.run()
  
      # Recreate DummySavable(), its tf.Variable is initialized to 0.
      x = DummySaveable()
      # Recreate the CheckpointingRunner, which will restore DummySavable() to 1.
      tf2_savers.CheckpointingRunner(
          wrapped=x, time_delta_minutes=0, directory=directory
      )
      # Check DummyVariable() was restored properly.
      np.testing.assert_array_equal(
          x.state["state"].numpy(), np.int32(1)
      )
  
imports: import os
  import re
  import time
  from unittest import mock
  from acme import specs
  from acme.testing import test_utils
  from acme.tf import networks
  from acme.tf import savers
  from acme.tf import utils
  from acme.utils import paths
  import launchpad
  import numpy
  import sonnet
  import tensorflow
  import tree
  from absl.testing import absltest
label_desc: Use image node_id 1 for calling the CheckpointingRunnerTest obj's underlying member method code with example usage: obj.test_signal_handling() without return types