pathlib: test_resolve_common fails on Windows w/ longusername

[izbyshev]

BPO	32907
Nosy	@pfmoore, @pitrou, @tjguk, @zware, @zooba, @izbyshev
PRs	bpo-32907: pathlib: Fix test_resolve_common failure on Windows #5812
Superseder	bpo-34977: Release Windows Store app containing Python

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2019-12-13.03:00:51.735>
created_at = <Date 2018-02-22.09:40:02.586>
labels = ['3.7', 'type-bug', 'tests', 'OS-windows']
title = 'pathlib: test_resolve_common fails on Windows w/ longusername'
updated_at = <Date 2019-12-13.03:00:51.734>
user = 'https://github.com/izbyshev'

bugs.python.org fields:

activity = <Date 2019-12-13.03:00:51.734>
actor = 'cheryl.sabella'
assignee = 'none'
closed = True
closed_date = <Date 2019-12-13.03:00:51.735>
closer = 'cheryl.sabella'
components = ['Tests', 'Windows']
creation = <Date 2018-02-22.09:40:02.586>
creator = 'izbyshev'
dependencies = []
files = []
hgrepos = []
issue_num = 32907
keywords = ['patch']
message_count = 1.0
messages = ['312545']
nosy_count = 6.0
nosy_names = ['paul.moore', 'pitrou', 'tim.golden', 'zach.ware', 'steve.dower', 'izbyshev']
pr_nums = ['5812']
priority = 'normal'
resolution = 'duplicate'
stage = 'resolved'
status = 'closed'
superseder = '34977'
type = 'behavior'
url = 'https://bugs.python.org/issue32907'
versions = ['Python 3.6', 'Python 3.7']

[izbyshev]

======================================================================
FAIL: test_resolve_common (test.test_pathlib.PathTest)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "C:\workspace\cpython-3.8a\lib\test\test_pathlib.py", line 1538, in test_resolve_common
    self._check_resolve_relative(p, P(d, 'foo', 'in', 'spam'), False)
  File "C:\workspace\cpython-3.8a\lib\test\test_pathlib.py", line 1477, in _check_resolve
    self.assertEqual(q, expected)
AssertionError: WindowsPath('C:/Users/longusername/AppData/Local/Temp/tmpbenaiqaa-[
13 chars]pam') != WindowsPath('C:/Users/LONGUS~1/AppData/Local/Temp/tmpbenaiqaa-
dirD/foo/in/spam')

======================================================================

The problem is that the temporary directory path returned by tempfile.mkdtemp() contains the username in "short" (8.3) format, but Path.resolve() converts short names to long ones (thanks to ntpath._getfinalpathname()).

Since os.path.realpath() still doesn't resolve symlinks on Windows (bpo-9949, bpo-14094), and users of ntpath._getfinalpathname() have to deal with '\\?\' prefix, I think I'll just use Path.resolve() for the tmp dir path as a workaround.