code: def test_CUDA_VISIBLE_DEVICES_should_be_empty_if_nothing_provided(
      self, gpu_check, get_gpu_count, os
  ):
      gpu_check.return_value = True
      get_gpu_count.return_value = 3
      os.environ.get.return_value = ""
      context = Context()
      os.environ.get.assert_called_with("CUDA_VISIBLE_DEVICES", "")
  
      self.assertEqual(context.gpus, [])
  
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 3 for calling the ExecutionContextTest obj's underlying member method code with example usage: obj.test_CUDA_VISIBLE_DEVICES_should_be_empty_if_nothing_provided(gpu_check, get_gpu_count, os) without return types