code: def test_inf(self):
      # Issue #11981
  
      formatter = EngFormatter(accuracy=1, use_eng_prefix=True)
      result = formatter(np.inf)
      assert result == "inf"
  
file_path: pandas/pandas/tests/io/formats/test_eng_formatting.py
imports: import numpy
  import pytest
  from pandas import DataFrame, reset_option, set_eng_float_format
  from pandas.io.formats.format import EngFormatter
label_desc: Use image node_id 9 for calling the TestEngFormatter obj's underlying member method code with example usage: obj.test_inf() without return types