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Reviewed:  https://review.opendev.org/470775
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=1eec451b1ba254ec4c43c77f79b0d2809d6cb9a5
Submitter: Zuul
Branch:    master

commit 1eec451b1ba254ec4c43c77f79b0d2809d6cb9a5
Author: Takashi NATSUME <natsume.takashi@xxxxxxxxxxxxx>
Date:   Mon Aug 19 18:11:48 2019 +0900

    Tests: autospecs all the mock.patch usages
    
    By default, mock.patch's autospec argument is None, meaning that
    there's no signature checking for the patched methods and functions.
    
    oslotest.mock_fixture.patch_mock_module fixes a few issues within
    mock.patch functions, as well as setting autospec=True by default,
    unless otherwise specified or new_callable, create, spec arguments
    are passed in.
    
    Co-Authored-By: Claudiu Belu <cbelu@xxxxxxxxxxxxxxxxxxxxxx>
    Change-Id: I4484e63c97bd1cdde3d88855eabe7545784f365e
    Closes-Bug: #1735588


** Changed in: nova
       Status: In Progress => Fix Released

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https://bugs.launchpad.net/bugs/1735588

Title:
  Mock autospec not used, or not used properly

Status in compute-hyperv:
  Fix Released
Status in networking-hyperv:
  Fix Released
Status in OpenStack Compute (nova):
  Fix Released
Status in os-win:
  Fix Released
Status in oslotest:
  Fix Released

Bug description:
  Description
  ===========

  In typical unit tests, almost all of the dependencies are mocked or
  patched (mock.patch), without any guarantee that the mocked methods
  actually exist, or if their signatures are respected (see below).
  Because of this, actual issues can easily be overlooked and missed, as
  the unit tests are wrongfully passing. [0]

  The mock.Mock class accepts a spec as an argument, which only solves
  half the problem: it only checks if an attribute exists, based on the
  given spec. It does not guarantee that the given attribute is actually
  a method, or if its signature is respected [1][2]. Some unit tests may
  pass the autospec argument, but mock doesn't support it at the moment.

  mock.patch, mock.patch.object, mock.patch.multiple accept an autospec
  argument, but because of a bug [3][4], it cannot be used properly.

  
  Steps to reproduce
  ==================

  import mock
  from mock.tests import testmock

  m = mock.Mock(spec=testmock.Something)

  # meth has the following signature:
  # def meth(self, a, b, c, d=None):
  m.meth()

  
  Expected result
  ===============

  TypeError should be raised.

  
  Actual result
  =============

  A mock object is returned.

  
  Proposal
  ========

  Bug reports have been issues for the bugs mentioned above, see
  [1][2][3][4], but until then, the mock library can be patched to
  include the following changes:

  - add autospec argument to mock.Mock and mock.MagicMock. Unit test should then pass the autospec argument whenever possible.
  - fix the mock.patch autospec issue.
  - enable mock.patch autospec by default, unless otherwise specified.

  
  Links
  =====

  [0] https://review.openstack.org/#/c/461689/
  [1] https://github.com/testing-cabal/mock/issues/393
  [2] https://bugs.python.org/issue30587
  [3] https://github.com/testing-cabal/mock/issues/396
  [4] https://bugs.python.org/issue32092

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