In doctest.py the following ordering is defined for the class DocTest:

 def __lt__(self, other): if not isinstance(other, DocTest): return NotImplemented return ((self.name, self.filename, self.lineno, id(self)) < (other.name, other.filename, other.lineno, id(other))) 

This is incorrect because the lineno field may be an integer and may be None, and comparisons between integers and None fail. Typically lineno is an integer, but _find_lineno explicitly can fall back to returning None so the field may be None:

 def _find_lineno(self, obj, source_lines): ... # We couldn't find the line number. return None 

Linked PRs

• gh-94722: fix DocTest.__eq__ for case of no line number on one side #112385
• [3.12] gh-94722: fix DocTest.__eq__ for case of no line number on one side (GH-112385) #112400
• [3.11] gh-94722: fix DocTest.__eq__ for case of no line number on one side (GH-112385) #112401