text: import logging
  import os
  import subprocess
  
  
  class DiffException(Exception):
      pass
  
  def diff_strings(output: str, expected_output: str) -> str:
  
      mdiff_path = "frontend_tests/zjsunit/mdiff.js"
      if not os.path.isfile(mdiff_path):  # nocoverage
          msg = "Cannot find mdiff for markdown diff rendering"
          logging.error(msg)
          raise DiffException(msg)
  
      command = ['node', mdiff_path, output, expected_output]
      diff = subprocess.check_output(command).decode('utf-8')
      return diff
  