code: def test_empty_span(self):
      text = "(19, 9, 4) Hadamard Designs and Their Residual Designs"
      doc = self.nlp(text)
      doc2 = self.detector(doc)
      assert len(doc2._.abbreviations) == 0
  
file_path: scispacy/tests/test_abbreviation_detection.py
imports: import unittest
  import spacy
  import pytest
  from scispacy.abbreviation import AbbreviationDetector, find_abbreviation, filter_matches
label_desc: Use image node_id 9 for calling the TestAbbreviationDetector obj's underlying member method code with example usage: obj.test_empty_span() without return types