code: def test_double_fault():
      labels = np.array([0, 0, 0, 0, 1, 1, 1])
      pred1 = np.array([1, 0, 1, 0, 0, 0, 0])
      pred2 = np.tile(np.array([1, 0, 0, 0, 1, 0, 0]), (5, 1))
  
      actual = double_fault(labels, pred1, pred2)
  
      assert (actual == np.full((5,), 3.0 / 7)).all()
  
file_path: DESlib/deslib/tests/util/test_diversity_batch.py
imports: import numpy
  import pytest
  from deslib.util.diversity_batch import _process_predictions, double_fault, Q_statistic, ratio_errors, agreement_measure, disagreement_measure, correlation_coefficient
label_desc: Use image node_id 6 for calling a global function with example usage: test_double_fault() without return types