gh-70186: Fix doctest badly handling unwrapable objects

Lib/doctest.py

@@ -1034,6 +1034,15 @@ def _find(self, tests, obj, name, module, source_lines, globs, seen):
             for valname, val in obj.__dict__.items():
                 valname = '%s.%s' % (name, valname)
 
+                try:
+                    inspect.unwrap(val)
+                except ValueError:
+                    # Do not catch the ValueError raised when a cycle is encountered.
+                    pass
+                except Exception as exc:
+                    raise ValueError("DocTestFinder.find: __wrapped__ threw %r: %r"
+                                     % (exc, type(val))) from None
+
                 # Recurse to functions & classes.
                 if ((self._is_routine(val) or inspect.isclass(val)) and
                     self._from_module(module, val)):

Lib/test/test_doctest/test_doctest.py

@@ -3498,6 +3498,29 @@ def test_syntax_error_with_incorrect_expected_note():
     """
 
 
+def test_unable_to_check_for_wrapped_attr():
+    """
+    Before gh-70186, DocTestFinder.find() failed when inspect.unwrap()
+    raised anything else but AttributeError while checking if a given
+    object had the __wrapped__ attribute.
+
+    >>> # An unwrapable class
+    >>> class UnwrapMeAndDie:
+    ...     def __getattr__(self, name):
+    ...         raise RuntimeError('boom')
+
+    >>> # A module using this class
+    >>> import types
+    >>> m = types.ModuleType('some_module')
+    >>> m.__dict__.update({'unwrap_me_not': UnwrapMeAndDie()})
+    >>> # DocTestFinder.find() should fail with a specific ValueError, nothing else
+    >>> finder = doctest.DocTestFinder()
+    >>> finder.find(m)  # doctest: +ELLIPSIS
+    Traceback (most recent call last):
+    ValueError: DocTestFinder.find: __wrapped__ threw RuntimeError('boom'): ...
+    """
+
+
 def load_tests(loader, tests, pattern):
     tests.addTest(doctest.DocTestSuite(doctest))
     tests.addTest(doctest.DocTestSuite())

Misc/NEWS.d/next/Tests/2024-11-29-10-24-16.gh-issue-70186.d_L_gd.rst

@@ -0,0 +1 @@
+Fix doctest badly handling unwrapable objects. Patch by Mickaël Schoentgen.