code: def testGridSearchAndEval(self):
      trials = self.generate_trials(
          {
              "run": "PPO",
              "config": {
                  "qux": tune.sample_from(lambda spec: 2 + 2),
                  "bar": grid_search([True, False]),
                  "foo": grid_search([1, 2, 3]),
                  "baz": "asd",
              },
          },
          "grid_eval",
      )
      trials = list(trials)
      self.assertEqual(len(trials), 6)
      self.assertEqual(
          trials[0].config,
          {
              "bar": True,
              "foo": 1,
              "qux": 4,
              "baz": "asd",
          },
      )
      self.assertEqual(
          trials[0].evaluated_params,
          {
              "bar": True,
              "foo": 1,
              "qux": 4,
          },
      )
      self.assertEqual(
          trials[0].experiment_tag, "0_bar=True,foo=1,qux=4"
      )
  
imports: import os
  import numpy
  import random
  import unittest
  import ray
  from ray.rllib import _register_all
  from ray import tune
  from ray.tune.result import DEFAULT_RESULTS_DIR
  from ray.tune.search import grid_search, BasicVariantGenerator
  from ray.tune.search.variant_generator import RecursiveDependencyError, _resolve_nested_dict
label_desc: Use image node_id 7 for calling the VariantGeneratorTest obj's underlying member method code with example usage: obj.testGridSearchAndEval() without return types