new_contents: """File for checking typing issues.
  
  This file is not executed, it is only checked by mypy to ensure that
  none of the code triggers any mypy errors.
  """
  import pytest
  
  
  # Issue #7488.
  @pytest.mark.xfail(raises=RuntimeError)
  def check_mark_xfail_raises() -> None:
      pass
  
subject: add a file for checking no mypy errors