unexpected successes are not output

[rbtcollins]

BPO	22815
Nosy	@rbtcollins, @ezio-melotti, @voidspace, @serhiy-storchaka, @iritkatriel
PRs	bpo-22815: Print unexpected successes in summary in TextTestResult #30138

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

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GitHub fields:

assignee = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2021-12-26.11:23:43.418>
created_at = <Date 2014-11-07.10:21:48.117>
labels = ['type-feature', 'library', '3.11']
title = 'unexpected successes are not output'
updated_at = <Date 2021-12-26.11:23:43.418>
user = 'https://github.com/rbtcollins'

bugs.python.org fields:

activity = <Date 2021-12-26.11:23:43.418>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2021-12-26.11:23:43.418>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2014-11-07.10:21:48.117>
creator = 'rbcollins'
dependencies = []
files = []
hgrepos = []
issue_num = 22815
keywords = ['patch']
message_count = 11.0
messages = ['230783', '407833', '407834', '408679', '408681', '408683', '408685', '408689', '408690', '408693', '409190']
nosy_count = 5.0
nosy_names = ['rbcollins', 'ezio.melotti', 'michael.foord', 'serhiy.storchaka', 'iritkatriel']
pr_nums = ['30138']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue22815'
versions = ['Python 3.11']

[rbtcollins]

Unexpected successes cause failures, but we don't output details about them at the end of the run.

From https://code.google.com/p/unittest-ext/issues/detail?id=22

A complicating factor is that we don't have a backtrace to show - but we may have captured stdout/stderr or in future various test attachments to show.

[iritkatriel]

I think this has been fixed:

% cat mm.py
import unittest

class TestStringMethods(unittest.TestCase):

    @unittest.expectedFailure
    def test_upper(self):
        self.assertEqual(2, 2)

if __name__ == '__main__':
    unittest.main()

% ./python.exe mm.py
x
----------------------------------------------------------------------
Ran 1 test in 0.001s

OK (expected failures=1)
iritkatriel@Irits-MBP cpython % vi mm.py
iritkatriel@Irits-MBP cpython % ./python.exe mm.py
u
----------------------------------------------------------------------
Ran 1 test in 0.000s

FAILED (unexpected successes=1)

[iritkatriel]

Or do you mean that there should be more output?

[iritkatriel]

In verbose mode we do get output like the one in the code.google issue:

% cat tmp.py

import unittest

class TestStringMethods(unittest.TestCase):

    @unittest.expectedFailure
    def test_upper(self):
        self.assertEqual(2, 2)

    def test_lower(self):
        return

if __name__ == '__main__':
    unittest.main()

% ./python.exe -m tmp -v
test_lower (main.TestStringMethods) ... ok
test_upper (main.TestStringMethods) ... unexpected success

[iritkatriel]

I don't think adding more information from the test would be helpful - when a test fails you have (and need) information about what happened. But when a test succeeds the code of the test basically tells you what happened - all the assertions passed.

I think we can close this.

[serhiy-storchaka]

I think the OP means that test details (test description, traceback, captured output) are printed for ERROR and FAIL in TextTestResult.printErrors(). Other possible results besides error and failure are success, skipped, expected failure and unexpected success. Success, skipped and expected failure are expected, they do not cause total failure, but unexpected success is different. Result.wasSuccessful() returns False if there are any errors, failures or unexpected successes. But unlike errors and failures we do not have any details about unexpected successes. It looks like oversight to me.

Yes, there are no traceback for unexpected success, but at least we can output the test description and captured output.

[serhiy-storchaka]

There are no other details for unexpected successes, only test descriptions.

[iritkatriel]

Yes, this is why I don’t understand the request here. When a test fails you know which assertion was violated or which line raised an exception. When a multi line test succeeds, you don’t know which line was supposed to fail.

[iritkatriel]

I know that in unittest2 an unexpected success did not cause the test to fail (when we moved from unittest2 to unittest at work we got test failures due to unexpected successes that previously did not show up). I don't know the whole history of how unittest2 came to be, I think it was a clone of an older copy of unittest? Maybe that it the background for this issue?

[serhiy-storchaka]

Unless you tun tests in verbose mode you do not know which of tests was unexpectedly successful. And even in the verbose mode it is not easy to find that test in long output.

Yes, unexpected successes considered successes in earlier versions. See bpo-20165.

You can find many interesting when read git logs.

[serhiy-storchaka]

New changeset 1944434 by Serhiy Storchaka in branch 'main':
bpo-22815: Print unexpected successes in summary in TextTestResult (GH-30138)
1944434