code: def test_val_split():
      datamodule = DataModule(
          Input(RunningStage.TRAINING, [1] * 100),
          batch_size=2,
          num_workers=0,
          val_split=0.2,
      )
  
      assert len(datamodule.train_dataset) == 80
      assert len(datamodule.val_dataset) == 20
  
imports: from dataclasses import dataclass
  from typing import Callable, Dict
  from unittest.mock import MagicMock, NonCallableMock, patch
  import numpy
  import pytest
  import torch
  from flash import Task, Trainer
  from flash.core.data.data_module import DataModule, DatasetInput
  from flash.core.data.io.input import Input
  from flash.core.data.io.input_transform import InputTransform
  from flash.core.utilities.imports import _TOPIC_CORE_AVAILABLE, _TOPIC_IMAGE_AVAILABLE, _TORCHVISION_AVAILABLE
  from flash.core.utilities.stages import RunningStage
  from pytorch_lightning import seed_everything
  from torch.utils.data import Dataset
  from tests.helpers.boring_model import BoringModel
label_desc: Use image node_id 5 for calling a global function with example usage: test_val_split() without return types