code: def test_louvain_nx_graph_with_isolated_nodes():
      # Cluster IDs are expected to unique if all nodes are isolated
      G = nx.Graph()
      G.add_nodes_from(range(5))
      result, _ = cugraph.louvain(G)
      assert set(result.keys()) == set(G.nodes)
      assert len(set(result.values())) == G.number_of_nodes()
  
      # A graph with 5 nodes, where 3 of the nodes are isolated
      G.add_edge(1, 2)
      result, _ = cugraph.louvain(G)
      assert set(result.keys()) == set(G.nodes)
      assert len(set(result.values())) == G.number_of_nodes() - 1
  
file_path: cugraph/python/cugraph/cugraph/tests/community/test_louvain.py
imports: import gc
  import time
  import pytest
  import networkx
  import cugraph
  import cupyx
  import cudf
  from cugraph.testing import utils, UNDIRECTED_DATASETS
  from cugraph.datasets import karate_asymmetric
label_desc: Use image node_id 7 for calling a global function with example usage: test_louvain_nx_graph_with_isolated_nodes() without return types