docstr: Default to one GPU if not explicitly requested
docstr_tok: ["Default","to","one","GPU","if","not","explicitly","requested"]
code: def test_gpu_default(self, mock_available, mock_get_gpus):
      """Default to one GPU if not explicitly requested"""
  
      mock_available.return_value = True
      mock_get_gpus.return_value = ["0"]
  
      tf_args = self.parser.parse_args([])
  
      map_fn = TFSparkNode.run(
          self.default_fn,
          tf_args,
          self.cluster_meta,
          self.tensorboard,
          self.log_dir,
          self.queues,
          self.background,
      )
      map_fn([0])
      self.assertEqual(os.environ["CUDA_VISIBLE_DEVICES"], "0")
      mock_get_gpus.assert_called_with(1, 0, format=gpu_info.AS_LIST)
  
file_path: TensorFlowOnSpark/tests/test_TFSparkNode.py
imports: import argparse
  import os
  import random
  import unittest
  from tensorflowonspark import gpu_info, reservation, TFSparkNode
  from unittest.mock import patch
label_desc: Use image node_id 6 for calling the TFSparkNodeTest obj's underlying member method code with example usage: obj.test_gpu_default(mock_available, mock_get_gpus) without return types