code: def test_candidate_generation(self):
      self.test_subdirectory = os.path.join(
          flags.FLAGS.test_tmpdir, self.id()
      )
      shutil.rmtree(self.test_subdirectory, ignore_errors=True)
      os.mkdir(self.test_subdirectory)
  
      subnetwork_generator = _subnetwork_generator(
          self.test_subdirectory
      )
      subnetwork_builders = subnetwork_generator.generate_candidates(
          previous_ensemble=None,
          # The following arguments are unused by
          # quetzal.Generator.
          iteration_number=0,
          previous_ensemble_reports=[],
          all_reports=[],
      )
      self.assertEqual(1, len(subnetwork_builders))
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import os
  import shutil
  from absl import flags
  from absl.testing import parameterized
  import adanet
  from adanet.research.improve_nas.trainer import improve_nas
  import numpy
  import tensorflow.compat.v1
label_desc: Use image node_id 1 for calling the QuetzalGeneratorTest obj's underlying member method code with example usage: obj.test_candidate_generation() without return types