code: def test_path_list(self):
      with self.assertRaisesRegex(
          UnsupportedError, "must be preceded by a join"
      ):
          PathList(output_transform="foo")
  
      # Test __init__
      A = IdentityPath()
      B = IdentityPath()
      module_list = ModuleList((A, B))
      path_list = PathList(paths=list(module_list))
      self.assertTrue(path_list.paths is not module_list)
  
      path_list = PathList(paths=module_list)
      self.assertIs(path_list.paths, module_list)
  
      # Test __call__
      x = torch.rand(3, device=self.device)
      output = path_list(x)
      self.assertIsInstance(output, list)
      self.assertTrue(x.equal(output.pop()))
      self.assertTrue(x.equal(output.pop()))
      self.assertTrue(not output)
  
      path_list.join = torch.stack
      output = path_list(x)
      self.assertIsInstance(output, torch.Tensor)
      self.assertEqual(output.shape, (2,) + x.shape)
      self.assertTrue(output.eq(x).all())
  
      # Test `list` methods
      self.assertEqual(len(path_list), 2)
      for key, (path, path_0) in enumerate(
          zip(path_list, path_list.paths)
      ):
          self.assertEqual(1, len({path, path_0, path_list[key]}))
  
      path_list[1] = A  # test __setitem__
      self.assertIs(path_list.paths[1], A)
  
      del path_list[1]  # test __delitem__
      self.assertEqual((A,), tuple(path_list))
  
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 2 for calling the TestGenericPaths obj's underlying member method code with example usage: obj.test_path_list() without return types