code: def test_n_neighbors_none():
      X = np.tile(np.arange(10).reshape(-1, 1), 3)
      y = np.array(5 * ["cat"] + 5 * ["dog"])
      knne = KNNE(n_neighbors=None)
      with pytest.raises(ValueError):
          knne.fit(X, y)
  
file_path: DESlib/deslib/tests/util/test_knne.py
imports: import pytest
  import numpy
  from deslib.util import faiss_knn_wrapper
  from deslib.util import KNNE
label_desc: Use image node_id 7 for calling a global function with example usage: test_n_neighbors_none() without return types