[Python-checkins] [python/cpython] e78dc0: [3.5] bpo-29403: Fix mock's broken autospec behavi...

[GitHub]

  Branch: refs/heads/3.5
  Home:   https://github.com/python/cpython
  Commit: e78dc0aaf03cd98373910150c2d35418cf938254
      https://github.com/python/cpython/commit/e78dc0aaf03cd98373910150c2d35418cf938254
  Author: Berker Peksag <berker.peksag at gmail.com>
  Date:   2017-07-22 (Sat, 22 Jul 2017)

  Changed paths:
    M Lib/unittest/mock.py
    M Lib/unittest/test/testmock/testhelpers.py
    A Misc/NEWS.d/next/Library/2017-07-20-02-29-49.bpo-29403.3RinCV.rst

  Log Message:
  -----------
  [3.5] bpo-29403: Fix mock's broken autospec behavior on method-bound builtin functions (GH-3)

Cython will, in the right circumstances, offer a MethodType instance
where im_func is a builtin function. Any instance of MethodType is
automatically assumed to be a Python-defined function (more
specifically, a function that has an inspectable signature), but
_set_signature was still conservative in its assumptions. As a result
_set_signature would return early with None instead of a mock since
the im_func had no inspectable signature. This causes problems
deeper inside mock, as _set_signature is assumed to _always_
return a mock, and nothing checked its return value.

In similar corner cases, autospec will simply not check the spec of the
function, so _set_signature is amended to now return early with the
original, not-wrapped mock object.

Patch by Aaron Gallagher.

(cherry picked from commit 856cbcc12f2e4cca93af5dc7ed6bcea4dd942f10)