code: def test_confusion_matrix_value(records, preds):
      confusion_matrix = SimpleConfusionMatrix()
      predictions = [
          Prediction(prediction_record, record)
          for prediction_record, record in zip(preds, records)
      ]
      confusion_matrix.accumulate(predictions)
      dummy_result = confusion_matrix.finalize()
      cm_result = confusion_matrix.confusion_matrix
      expected_result = np.diagflat([0, 0, 2, 1])
      assert dummy_result["dummy_value_for_fastai"] == -1
      assert np.equal(cm_result, expected_result).all()
  
file_path: icevision/tests/metrics/test_confusion_matrix.py
imports: import pytest
  from icevision.all import *
  from icevision.metrics.confusion_matrix.confusion_matrix_utils import *
label_desc: Use image node_id 12 for calling a global function with example usage: test_confusion_matrix_value(records, preds) without return types