[EuroPython 2019]

For some reason, an object could raise an error different from AttributeError when checking for its __wrapped__ attribute.

This patch silences any errors coming from the underlying call to inpect.unwrap() and, if verbose is set to True, prints out the exception.

Thanks to @mpaolini for helping me with the reproduction test case.

As of the current patch state, I followed R. David Murray (I do not find his GH nick) sentence from his last comment on the BPO:

it should be capturing that and probably other errors and reporting them, instead of just producing a traceback, I think.

Another solution would be to patch inspect.unwrap() like:

diff --git a/Lib/inspect.py b/Lib/inspect.py
index 99a580bd2f..f359b0558a 100644
--- a/Lib/inspect.py
+++ b/Lib/inspect.py
@@ -507,11 +507,16 @@ def unwrap(func, *, stop=None):
 
     """
     if stop is None:
-        def _is_wrapper(f):
+        def __is_wrapper(f):
             return hasattr(f, '__wrapped__')
     else:
-        def _is_wrapper(f):
+        def __is_wrapper(f):
             return hasattr(f, '__wrapped__') and not stop(f)
+    def _is_wrapper(f):
+        try:
+            return __is_wrapper(f)
+        except Exception:
+            return False
     f = func  # remember the original func for error reporting
     # Memoise by id to tolerate non-hashable objects, but store objects to
     # ensure they aren't destroyed, which would allow their IDs to be reused.

But we then loose details and nobody could know that there is an issue somewhere.
I did not want to raise a specific error from there only for doctest (but it is still totally doable).

Yet another solution would to raise from doctest instead of printing. Such as:

raise ValueError(f"DocTestFinder.find: __wrapped__ threw {exc!r}: {type(val)!r}")

As it is done few lines below when doctest cannot deal with certain objects or certains conditions.
This would keep some uniformization in how doctest handle bad cases.

👀 I need external eyes to decide on what is the best solution to use :) (I had to leave the sprints before having time to speak with a core dev)

https://bugs.python.org/issue25998

• Issue: doctest terminates when accessing __wrapped__ raises an error #70186