[openstack-dev] [all][tests] Fix it friday! [mock failure in CI]

Robert Collins robertc at robertcollins.net
Fri Jul 10 07:45:10 UTC 2015

Good news everybody, mock 1.1.0 is now out. This backports all the
improvements over the last couple of years, making it fully
synchronised with cPython master. Yay.

Bad news. Lots of unit tests jobs have suffered falled from this.

But - none of the things I've looked into so far are bugs in mock 1.1.0.

One of the improvements in mock is to fail when a bad method is called.

Consider this: https://review.openstack.org/#/c/200384/1/taskflow/tests/unit/test_engine_helpers.py

Note the old method: mock_import.assert_called_onec_with(name)

That method never existed. onec is a typo :).

mock 1.0.1 silently accepts that - thats part of its job. But, its a
very fragile API.

1.1.0 makes that an error, for methods with assert prefixes - unless
unsafe is specifically requested. So a big chunk of the failing tests
are tests that were not testing anything *at all*.
One common exampled of that is 'assert_called' - another method that
never ever existed. All our tests using that were testing nothing at

Neutron is failing on a bunch of tests that accessed a private
function inside mock. I'm surprised reviewers didn't spot this, but
_patch isn't part of the public API, and never was.

Tempest seems to be failing due to a different object being returned -
I haven't dug deep enough to describe the cause in more detail.

We can probably pin mock back to 1.0.1 locally within projects to gain
breathing room, but given the API improvements in 1.1.0 (see below[1]
as readthedocs is failing to build it due to having an old pip in
their virtualenvs :/) - I think we'll be much better off adopting it
as quickly as we can. NB: with this release we don't need to use
'unittest.mock' for Python3.4 - we can just standardise on using
'mock' across the board, which is much simpler and easier to reason
about (same codebase everywhere[2])

[2]: Python 2.6 support was dropped in 1.1.0, so we need to use
markers to select 1.0.1 for the remaining 2.6 gate jobs. (We should
kill those of asap).
- Issue #23310: Fix MagicMock's initializer to work with __methods__, just
  like configure_mock().  Patch by Kasia Jachim.

- Issue #23568: Add rdivmod support to MagicMock() objects.
  Patch by Håkan Lövdahl.

- Issue #23581: Add matmul support to MagicMock. Patch by Håkan Lövdahl.

- Issue #23326: Removed __ne__ implementations.  Since fixing default __ne__
  implementation in issue #21408 they are redundant. *** NOT BACKPORTED ***

- Issue #21270: We now override tuple methods in mock.call objects so that
  they can be used as normal call attributes.

- Issue #21256: Printout of keyword args should be in deterministic order in
  a mock function call. This will help to write better doctests.

- Issue #21262: New method assert_not_called for Mock.
  It raises AssertionError if the mock has been called.

- Issue #21238: New keyword argument `unsafe` to Mock. It raises
  `AttributeError` incase of an attribute startswith assert or assret.

- Issue #21239: patch.stopall() didn't work deterministically when the same
  name was patched more than once.

- Issue #21222: Passing name keyword argument to mock.create_autospec now

- Issue #17826: setting an iterable side_effect on a mock function created by
  create_autospec now works. Patch by Kushal Das.

- Issue #17826: setting an iterable side_effect on a mock function created by
  create_autospec now works. Patch by Kushal Das.

- Issue #20968: unittest.mock.MagicMock now supports division.
  Patch by Johannes Baiter.

- Issue #20189: unittest.mock now no longer assumes that any object for
  which it could get an inspect.Signature is a callable written in Python.
  Fix courtesy of Michael Foord.

- Issue #17467: add readline and readlines support to mock_open in

- Issue #17015: When it has a spec, a Mock object now inspects its signature
  when matching calls, so that arguments can be matched positionally or
  by name.

- Issue #15323: improve failure message of Mock.assert_called_once_with

- Issue #14857: fix regression in references to PEP 3135 implicit __class__
  closure variable (Reopens issue #12370)

- Issue #14295: Add unittest.mock


Robert Collins <rbtcollins at hp.com>
Distinguished Technologist
HP Converged Cloud

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