class_docstr: Test vis
code: def setUp(self) -> None:
      self.mock_img = Image.new(mode="RGB", size=(20, 20))
      self.class1_path = Path(cur_dir) / "root" / "class_1"
      self.root_dir = str(Path(cur_dir) / "root")
      Path.mkdir(self.class1_path, parents=True, exist_ok=True)
      self.img_path = self.class1_path / "mock_img.jpg"
      self.mock_img.save(self.img_path)
  
imports: import unittest
  import torch
  from pathlib import Path
  from torchvision import transforms
  from torchvision.models import resnet18
  from towhee.utils.pil_utils import PILImage
  from towhee.utils.matplotlib_utils import matplotlib
  from towhee.trainer.utils.plot_utils import image_folder_sample_show, image_folder_statistic, show_transform, plot_lrs_for_config, plot_lrs_for_scheduler, interpret_image_classification
  from towhee.trainer.training_config import TrainingConfig
  from torch import nn
  from torch.optim.lr_scheduler import StepLR
label_desc: Use image node_id 1 for calling the TestVisualizationUtil obj's underlying member method code with example usage: obj.setUp() without return types