testing: make the atexit monkeypatch more robust, needed for pytest 6

Author: The-Compiler

testing/conftest.py

@@ -9,9 +9,12 @@ def _divert_atexit(request, monkeypatch):
     import atexit
     atexit_fns = []
 
+    def atexit_register(func, *args, **kwargs):
+        atexit_fns.append(lambda: func(*args, **kwargs))
+
     def finish():
         while atexit_fns:
             atexit_fns.pop()()
 
-    monkeypatch.setattr(atexit, "register", atexit_fns.append)
+    monkeypatch.setattr(atexit, "register", atexit_register)
     request.addfinalizer(finish)