code: def test_read(self):
      # Test for read only operations on mapping
      p = self._empty_mapping()
      p1 = dict(p)  # workaround for singleton objects
      d = self._full_mapping(self.reference)
      if d is p:
          p = p1
      # Indexing
      for key, value in self.reference.items():
          self.assertEqual(d[key], value)
      knownkey = next(iter(self.other.keys()))
      self.assertRaises(KeyError, lambda: d[knownkey])
      # len
      self.assertEqual(len(p), 0)
      self.assertEqual(len(d), len(self.reference))
      # __contains__
      for k in self.reference:
          self.assertIn(k, d)
      for k in self.other:
          self.assertNotIn(k, d)
      # cmp
      self.assertTrue(
          p == p
      )  # NB: don't use assertEqual, that doesn't actually use ==
      self.assertTrue(d == d)
      self.assertTrue(p != d)
      self.assertTrue(d != p)
      # bool
      if p:
          self.fail("Empty mapping must compare to False")
      if not d:
          self.fail("Full mapping must compare to True")
  
      # keys(), items(), iterkeys() ...
      def check_iterandlist(iter, lst, ref):
          self.assertTrue(hasattr(iter, "__next__"))
          self.assertTrue(hasattr(iter, "__iter__"))
          x = list(iter)
          self.assertTrue(set(x) == set(lst) == set(ref))
  
      check_iterandlist(
          iter(d.keys()), list(d.keys()), self.reference.keys()
      )
      check_iterandlist(iter(d), list(d.keys()), self.reference.keys())
      check_iterandlist(
          iter(d.values()), list(d.values()), self.reference.values()
      )
      check_iterandlist(
          iter(d.items()), list(d.items()), self.reference.items()
      )
      # get
      key, value = next(iter(d.items()))
      knownkey, knownvalue = next(iter(self.other.items()))
      self.assertEqual(d.get(key, knownvalue), value)
      self.assertEqual(d.get(knownkey, knownvalue), knownvalue)
      self.assertNotIn(knownkey, d)
  
imports: import copy
  import gc
  import random
  import threading
  import unittest
  import torch
  from torch.testing._internal.common_utils import find_library_location, IS_FBCODE, IS_MACOS, IS_SANDCASTLE, IS_WINDOWS, run_tests, TestCase
  from torch.utils.weak import _WeakHashRef, WeakIdKeyDictionary
label_desc: Use image node_id 6 for calling the WeakKeyDictionaryScriptObjectTestCase obj's underlying member method code with example usage: obj.test_read() without return types