code: def test_path_dict(self):
      with self.assertRaisesRegex(
          UnsupportedError, "must be preceded by a join"
      ):
          PathDict(output_transform="foo")
  
      A = IdentityPath()
      B = IdentityPath()
  
      # Test __init__
      module_dict = ModuleDict({"0": A, "1": B})
      path_dict = PathDict(paths={"0": A, "1": B})
      self.assertTrue(path_dict.paths is not module_dict)
  
      path_dict = PathDict(paths=module_dict)
      self.assertIs(path_dict.paths, module_dict)
  
      # Test __call__
      x = torch.rand(3, device=self.device)
      output = path_dict(x)
      self.assertIsInstance(output, dict)
      self.assertTrue(x.equal(output.pop("0")))
      self.assertTrue(x.equal(output.pop("1")))
      self.assertTrue(not output)
  
      path_dict.join = torch.stack
      output = path_dict(x)
      self.assertIsInstance(output, torch.Tensor)
      self.assertEqual(output.shape, (2,) + x.shape)
      self.assertTrue(output.eq(x).all())
  
      # Test `dict`` methods
      self.assertEqual(len(path_dict), 2)
      for key, val, (key_0, val_0), (key_1, val_1), key_2 in zip(
          path_dict,
          path_dict.values(),
          path_dict.items(),
          path_dict.paths.items(),
          path_dict.keys(),
      ):
          self.assertEqual(1, len({key, key_0, key_1, key_2}))
          self.assertEqual(1, len({val, val_0, val_1, path_dict[key]}))
  
      path_dict["1"] = A  # test __setitem__
      self.assertIs(path_dict.paths["1"], A)
  
      del path_dict["1"]  # test __delitem__
      self.assertEqual(("0",), tuple(path_dict))
  
file_path: botorch/test/sampling/pathwise/test_paths.py
imports: from __future__ import annotations
  import torch
  from botorch.exceptions.errors import UnsupportedError
  from botorch.sampling.pathwise.paths import PathDict, PathList, SamplePath
  from botorch.utils.testing import BotorchTestCase
  from torch.nn import ModuleDict, ModuleList
label_desc: Use image node_id 1 for calling the TestGenericPaths obj's underlying member method code with example usage: obj.test_path_dict() without return types