test_trace fails with -S

[pitrou]

BPO	19398
Nosy	@terryjreedy, @pitrou, @serhiy-storchaka, @vajrasky, @tdsmith
PRs	[Do Not Merge] Convert Misc/NEWS so that it is managed by towncrier #552
Files	emergency_patch_for_test_trace.patch remove_extra_slash_from_sys_path.patch remove_extra_slash_from_sys_path_v2.patch remove_extra_slash_from_sys_path_v3.patch

^{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 = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2016-11-11.12:02:17.455>
created_at = <Date 2013-10-25.19:43:53.096>
labels = ['3.7', 'type-bug', 'tests']
title = 'test_trace fails with -S'
updated_at = <Date 2017-03-31.16:36:09.121>
user = 'https://github.com/pitrou'

bugs.python.org fields:

activity = <Date 2017-03-31.16:36:09.121>
actor = 'dstufft'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2016-11-11.12:02:17.455>
closer = 'serhiy.storchaka'
components = ['Tests']
creation = <Date 2013-10-25.19:43:53.096>
creator = 'pitrou'
dependencies = []
files = ['32366', '32367', '32460', '45422']
hgrepos = []
issue_num = 19398
keywords = ['patch']
message_count = 7.0
messages = ['201286', '201313', '201314', '201947', '201962', '280500', '280572']
nosy_count = 6.0
nosy_names = ['terry.reedy', 'pitrou', 'python-dev', 'serhiy.storchaka', 'vajrasky', 'tdsmith']
pr_nums = ['552']
priority = 'low'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue19398'
versions = ['Python 2.7', 'Python 3.5', 'Python 3.6', 'Python 3.7']

[pitrou]

$ ./python -S -m test test_trace
[1/1] test_trace
test test_trace failed -- Traceback (most recent call last):
  File "/home/antoine/cpython/default/Lib/test/test_trace.py", line 313, in test_coverage
    self.assertTrue("pprint.cover" in files)
AssertionError: False is not true

[vajrasky]

This is the "emergency" patch to solve this issue.

The main issue is,

[sky@localhost cpython]$ ./python -Sc "import sys; print(sys.path)"
['', '/usr/local/lib/python34.zip', '/home/sky/Code/python/programming_language/cpython/Lib/', '/home/sky/Code/python/programming_language/cpython/Lib/plat-linux', '/home/sky/Code/python/programming_language/cpython/build/lib.linux-x86_64-3.4-pydebug']
[sky@localhost cpython]$ ./python -c "import sys; print(sys.path)"
['', '/usr/local/lib/python34.zip', '/home/sky/Code/python/programming_language/cpython/Lib', '/home/sky/Code/python/programming_language/cpython/Lib/plat-linux', '/home/sky/Code/python/programming_language/cpython/build/lib.linux-x86_64-3.4-pydebug', '/home/sky/.local/lib/python3.4/site-packages']

Let me "zoom" it for you.

[sky@localhost cpython]$ ./python -Sc "import sys; print(sys.path[2])"
/home/sky/Code/python/programming_language/cpython/Lib/
[sky@localhost cpython]$ ./python -c "import sys; print(sys.path[2])"
/home/sky/Code/python/programming_language/cpython/Lib

The "extra" slash is the culprit. I need to investigate whether this is deliberate or not.

[vajrasky]

I finally found the main culprit which puts extra '/' in my sys.path. The patch removed the extra '/' and also fixed this test automatically.

[terryjreedy]

The test should use the more specific assertXyz method:
self.assertIn("pprint.cover", files)

The error message would then be the more informative
AssertionError: 'pprint.cover' not found in <files listed>

[vajrasky]

Attached the patch to accommodate Terry J. Reedy's request.

[serhiy-storchaka]

The separator is needed if the relative path is not empty and the prefix doesn't end with the separator.

This patch seems also fixes most problems of bpo-28655.

[python-dev]

New changeset db220f2df5a9 by Serhiy Storchaka in branch '3.5':
Issue bpo-19398: Extra slash no longer added to sys.path components in case of
https://hg.python.org/cpython/rev/db220f2df5a9

New changeset 1a88baaed7a0 by Serhiy Storchaka in branch '3.6':
Issue bpo-19398: Extra slash no longer added to sys.path components in case of
https://hg.python.org/cpython/rev/1a88baaed7a0

New changeset 82607e7c24c7 by Serhiy Storchaka in branch 'default':
Issue bpo-19398: Extra slash no longer added to sys.path components in case of
https://hg.python.org/cpython/rev/82607e7c24c7

New changeset 237ef36fb1bb by Serhiy Storchaka in branch '2.7':
Issue bpo-19398: Extra slash no longer added to sys.path components in case of
https://hg.python.org/cpython/rev/237ef36fb1bb