add tests for test.support

[brettcannon]

BPO	11049
Nosy	@vsajip, @ncoghlan, @pitrou, @giampaolo, @ezio-melotti, @merwok, @bitdancer, @sandrotosi
Files	test_support.patch test_support.patch test_support.patch unnamed

^{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/bitdancer'
closed_at = <Date 2013-01-25.20:09:50.264>
created_at = <Date 2011-01-28.19:05:31.424>
labels = ['easy', 'type-bug', 'tests']
title = 'add tests for test.support'
updated_at = <Date 2013-01-25.20:09:50.263>
user = 'https://github.com/brettcannon'

bugs.python.org fields:

activity = <Date 2013-01-25.20:09:50.263>
actor = 'r.david.murray'
assignee = 'r.david.murray'
closed = True
closed_date = <Date 2013-01-25.20:09:50.264>
closer = 'r.david.murray'
components = ['Tests']
creation = <Date 2011-01-28.19:05:31.424>
creator = 'brett.cannon'
dependencies = []
files = ['20596', '20602', '20855', '22763']
hgrepos = []
issue_num = 11049
keywords = ['patch', 'easy']
message_count = 30.0
messages = ['127322', '127323', '127379', '127381', '127383', '127407', '127409', '127420', '129122', '129155', '130651', '135260', '140928', '140929', '140930', '140931', '140934', '140977', '140980', '141132', '141247', '141526', '141544', '141584', '141593', '141594', '141607', '141608', '180609', '180620']
nosy_count = 10.0
nosy_names = ['vinay.sajip', 'ncoghlan', 'pitrou', 'giampaolo.rodola', 'ezio.melotti', 'eric.araujo', 'r.david.murray', 'eli.bendersky', 'sandro.tosi', 'python-dev']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue11049'
versions = ['Python 3.3']

Linked PRs

• gh-55258: Reenable support test_get_original_stdout() #139499
• gh-55258: Skip tests of stdout status on mobile platforms #140401

[brettcannon]

It seems a little negligent that test.support has no tests. The test.test_support name is available in py3k and backporting issues to 2.7 shouldn't be a problem (rare chance something does happen it can be handling manually). There doesn't seem to be any reason not to make sure that proper unit testing is being done short of just laziness on our parts.

And if this does occur it should probably be listed as an essential test in regrtest.

[brettcannon]

I should note that I am not suggesting that test.support suddenly be considered a module with a stable API that the public can use. Simply that we take the proper measures to make sure the code in there does what is expected.

[giampaolo]

Attached is a patch which tests about half the API.
Certain functions are not documented and/or it's not clear what they do, for others it seems unlikely they are actually used nowadays (although I haven't checked).
Also, it probably makes sense to get rid of some functions which look very old or completely useless.

[elibendersky]

Giampaolo, FYI I'm also working (bpo-11015) in parallel on documenting some of the undocumented functions in Doc/library/test.rst that look useful to me. I think we can collaborate here to make sure they're both documented and tested.

I'll review your patch

P.S. see discussion on pydev about the removal of fcmp

[elibendersky]

Giampaolo,

The patch looks good. Some minor comments below:

• class TestCase(unittest.TestCase): -> why not give the test class a more useful name?
• import_fresh_module is tested similarly to import_module - can't a test be added that it indeed performs its "special sauce"?
• test_DirsOnSysPath: you may want to use assertIn and assertNotIn here. [these were added to Python in 3.1]
• test_python_is_optimized: you may want to use assertIsInstance here.

[ncoghlan]

test_warnings actually includes sanity checks for import_fresh_module - they could be adapted into a separate unit test easily enough.

[pitrou]

+ os.mkdir(os.path.join(TESTFN, TESTFN))

Please don't. This will break the day TESTFN becomes a non-trivial path.

+ def test_make_bad_fd(self):
+ fd = support.make_bad_fd()
+ self.assertRaises(OSError, os.write, fd, b"foo")

You should also check that the errno is EBADF.

[giampaolo]

• class TestCase(unittest.TestCase): -> why not give the test class a
  more useful name?

done

• import_fresh_module is tested similarly to import_module - can't a
  test be added that it indeed performs its "special sauce"?

Even by reading the source code I'm not sure what import_fresh_module does exactly.
Feel free to write a test for it if you want.

• test_DirsOnSysPath: you may want to use assertIn and assertNotIn here. [these
  were added to Python in 3.1]

done

• test_python_is_optimized: you may want to use assertIsInstance here.

done

•    os.mkdir(os.path.join(TESTFN, TESTFN))
  

Please don't. This will break the day TESTFN becomes a non-trivial path.

done

You should also check that the errno is EBADF.

Done. I just hope it's gonna be reliable on all platforms.

[giampaolo]

Can we commit this patch?

[bitdancer]

I agree that the docs for import_fresh_module are confusing. The code says there are sanity checks in test_heapq and test_warnings, so that code could presumably be used as a model for someone to develop a more complete stand-alone test (I haven't looked for that code myself). I'm not sure why we have both import_fresh_module and CleanImport, since they seem to do similar things (but differently!)

I started making comments on other tests and then realized it wasn't much more work to just update them myself. Extended patch attached.

[bitdancer]

Gah. I always check to see if the patch uploaded before I delete my working copy, but this time I didn't :( :(

I guess I'll come back to this during the sprints.