code: def test_caching(self, init=1, expect=4, expect_pre_cache=2):
      # check that we get the correct result (two lots of T so should get 4)
      x = init
      transforms = mt.Compose([T(), mt.RandIdentity(), T()])
      self.assertEqual(transforms(x), expect)
  
      # check we get correct result with CacheDataset
      x = [init]
      ds = CacheDataset(x, transforms)
      self.assertEqual(ds[0], expect)
  
      # check that the cached value is correct
      self.assertEqual(ds._cache[0], expect_pre_cache)
  
file_path: MONAI/tests/test_randidentity.py
imports: from __future__ import annotations
  import unittest
  import monai.transforms
  from monai.data import CacheDataset
  from tests.utils import TEST_NDARRAYS, NumpyImageTestCase2D, assert_allclose
label_desc: Use image node_id 2 for calling the TestIdentity obj's underlying member method code with example usage: obj.test_caching(init, expect, expect_pre_cache) without return types