code: def test_gpu_device_should_return_NO_GPU_if_GPU_not_available(
      self, gpu_check, os
  ):
      gpu_check.return_value = True
      os.environ.get.return_value = ""
      context = Context()
      os.environ.get.assert_called_with("CUDA_VISIBLE_DEVICES", "")
  
      self.assertEqual(context.gpu_device(), NO_GPU)
  
file_path: evadb/test/unit_tests/executor/test_execution_context.py
imports: import unittest
  from mock import patch
  from evadb.constants import NO_GPU
  from evadb.executor.execution_context import Context
label_desc: Use image node_id 5 for calling the ExecutionContextTest obj's underlying member method code with example usage: obj.test_gpu_device_should_return_NO_GPU_if_GPU_not_available(gpu_check, os) without return types