code: def test_recmetric_module(self):
      recmetric_module = _get_recmetric_module()
      scorer = LinearRegressionUCB(self.x_dim)
      policy = Policy(scorer=scorer, sampler=GreedyActionSampler())
      trainer = LinUCBTrainer(
          policy, recmetric_module=recmetric_module, log_every_n_steps=1
      )
  
      # hacky way to set the logger
      trainer.trainer = AttrDict()
      trainer.trainer.logger = TensorBoardLogger("/tmp/log_dir")
      trainer.trainer.global_step = 0
  
      trainer.training_step(self.batch, 0)
      trainer.training_step(self.batch, 1)
      trainer.on_train_epoch_end()
  
imports: import copy
  import unittest
  import numpy
  import numpy.testing
  import torch
  from libfb.py.collections import AttrDict
  from pytorch_lightning.loggers import TensorBoardLogger
  from reagent.core.types import CBInput
  from reagent.gym.policies.policy import Policy
  from reagent.gym.policies.samplers.discrete_sampler import GreedyActionSampler
  from reagent.models.linear_regression import LinearRegressionUCB
  from reagent.training.cb.linucb_trainer import LinUCBTrainer
  from reagent.training.cb.utils import add_chosen_arm_features
  from reagent.training.parameters import LinUCBTrainerParameters
  from torchrec.fb.metrics.meta_config import DefaultTaskInfo, MetricsConfig, QPSDef, RecMetricDef, RecMetricEnum
  from torchrec.fb.metrics.meta_metrics import generate_metric_module, RecMetricModule
label_desc: Use image node_id 8 for calling the TestLinUCB obj's underlying member method code with example usage: obj.test_recmetric_module() without return types