Unittest document is not clear on SetUpClass calls

[vrpolakatcisco]

BPO	36612
Nosy	@lisroach, @csabella, @tirkarthi, @vrpolakatcisco
PRs	gh-80793: Edit unittest.rst on SetUpClass calls #12798

^{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 = None
closed_at = None
created_at = <Date 2019-04-12.12:09:53.681>
labels = ['3.8', 'type-feature', '3.7', 'docs']
title = 'Unittest document is not clear on SetUpClass calls'
updated_at = <Date 2019-06-01.15:21:51.200>
user = 'https://github.com/vrpolakatcisco'

bugs.python.org fields:

activity = <Date 2019-06-01.15:21:51.200>
actor = 'cheryl.sabella'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2019-04-12.12:09:53.681>
creator = 'vrpolakatcisco'
dependencies = []
files = []
hgrepos = []
issue_num = 36612
keywords = ['patch']
message_count = 3.0
messages = ['340028', '340032', '344177']
nosy_count = 6.0
nosy_names = ['SilentGhost', 'docs@python', 'lisroach', 'cheryl.sabella', 'xtreak', 'vrpolakatcisco']
pr_nums = ['12798']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue36612'
versions = ['Python 3.7', 'Python 3.8']

[vrpolakatcisco]

One particular paragraph from unittest.rst is not clear enough:

"If you want the setUpClass and tearDownClass on base classes called then you must call up to them yourself. The implementations in TestCase are empty."

It has sparkled a debate here [0].

Example:
A class SuperTestCase, which inherits from unittest.TestCase, defines some non-trivial setUpClass class method. Then a class SubTestCase, which inherits from SuperTestCase, wants to have SuperTestCase.setUpClass executed as its setUpClass.
Does SubTestCase need to override setUpClass just to call SuperTestCase.setUpClass (as the paragraphs might suggest), or can it rely in inheritance to have it executed without overriding?

I will create GitHub PR soon.

[0] https://gerrit.fd.io/r/#/c/18579/1/test/test_sparse_vec.py@14

[SilentGhost]

Normal inheritance rules apply to TestCase and its subclasses, as can be demonstrated by a trivial example.

[csabella]

@XTreak or @lisroach, any thoughts? Thanks!

[willingc]

Closing since current documentation is clear and the associated PR was closed.