code: def test_add_nodes():
      g = GraphData()
      try:
          g.add_nodes(-1)
          fail_here()
      except AssertionError:
          pass
  
      g.add_nodes(10)
      assert g.get_node_num() == 10  # Test node number
  
      # Test reserved fields
      assert g.node_features["node_feat"] is None
      assert g.node_features["node_emb"] is None
      assert g.node_attributes[0]["node_attr"] is None
  
      g.node_features["zero"] = torch.ones(10)
      g.add_nodes(9)
      assert g.get_node_num() == 19
      assert torch.all(
          torch.eq(g.node_features["zero"][10:], torch.zeros(9))
      )
  
imports: import gc
  import time
  import matplotlib.pyplot
  import torch
  import torch.nn
  import pytest
  from ...data.data import GraphData, from_batch, from_dgl, to_batch
  from ...data.utils import EdgeNotFoundException, SizeMismatchException
label_desc: Use image node_id 2 for calling a global function with example usage: test_add_nodes() without return types