code: def test_invalid_config(self):
      config = self._get_valid_config()
  
      # Invalid num epochs
      bad_config = copy.deepcopy(config)
      bad_config["num_epochs"] = -1
      with self.assertRaises(ValueError):
          StepWithFixedGammaParamScheduler.from_config(bad_config)
  
      # Invalid num_decays
      bad_config["num_decays"] = 0
      with self.assertRaises(ValueError):
          StepWithFixedGammaParamScheduler.from_config(bad_config)
  
      # Invalid base_value
      bad_config = copy.deepcopy(config)
      bad_config["base_value"] = -0.01
      with self.assertRaises(ValueError):
          StepWithFixedGammaParamScheduler.from_config(bad_config)
  
      # Invalid gamma
      bad_config = copy.deepcopy(config)
      bad_config["gamma"] = [2]
      with self.assertRaises(ValueError):
          StepWithFixedGammaParamScheduler.from_config(bad_config)
  
file_path: ClassyVision/test/optim_param_scheduler_step_with_fixed_gamma_test.py
imports: import copy
  import unittest
  from classy_vision.optim.param_scheduler import build_param_scheduler, StepWithFixedGammaParamScheduler
label_desc: Use image node_id 2 for calling the TestStepWithFixedGammaScheduler obj's underlying member method code with example usage: obj.test_invalid_config() without return types