code: def test_sssp_unweighted_graph():
      karate = SMALL_DATASETS[0]
      G = karate.get_graph(ignore_weights=True)
  
      error_msg = (
          "'SSSP' requires the input graph to be weighted."
          "'BFS' should be used instead of 'SSSP' for unweighted graphs."
      )
  
      with pytest.raises(RuntimeError, match=error_msg):
          cugraph.sssp(G, 1)
  
imports: import gc
  import pytest
  import numpy
  import pandas
  import cudf
  import cupyx
  import cugraph
  import cupy
  from cupyx.scipy.sparse import coo_matrix
  from cupyx.scipy.sparse import csr_matrix
  from cupyx.scipy.sparse import csc_matrix
  from scipy.sparse import coo_matrix
  from scipy.sparse import csr_matrix
  from scipy.sparse import csc_matrix
  from pylibcugraph.testing.utils import gen_fixture_params_product
  from cugraph.testing import utils, get_resultset, load_resultset, UNDIRECTED_DATASETS, SMALL_DATASETS
label_desc: Use image node_id 19 for calling a global function with example usage: test_sssp_unweighted_graph() without return types