code: def test_double_fault_ones(example_diversity_ones_zeros):
      y, y_pred_ones, y_pred_zeros = example_diversity_ones_zeros
      df = double_fault(y, y_pred_ones, y_pred_ones)
      assert df == 9.0 / 15.0
  
imports: import sys
  import numpy
  import pytest
  from deslib.util.diversity import _process_predictions, double_fault, Q_statistic, ratio_errors, agreement_measure, disagreement_measure, correlation_coefficient
label_desc: Use image node_id 11 for calling a global function with example usage: test_double_fault_ones(example_diversity_ones_zeros) without return types