mypy_test.py: rework filter, exclude and --dir arguments (#8711)

tests/utils.py

@@ -1,12 +1,18 @@
 """Utilities that are imported by multiple scripts in the tests directory."""
 
 import os
+import re
 from functools import cache
 from pathlib import Path
 from typing import NamedTuple
 
 import tomli
 
+
+def strip_comments(text: str) -> str:
+    return text.split("#")[0].strip()
+
+
 try:
     from termcolor import colored as colored
 except ImportError:
@@ -46,6 +52,14 @@ def read_dependencies(distribution: str) -> tuple[str, ...]:
     return tuple(dependencies)
 
 
+# ====================================================================
+# Parsing the stdlib/VERSIONS file
+# ====================================================================
+
+
+VERSIONS_RE = re.compile(r"^([a-zA-Z_][a-zA-Z0-9_.]*): ([23]\.\d{1,2})-([23]\.\d{1,2})?$")
+
+
 # ====================================================================
 # Getting test-case directories from package names
 # ====================================================================