bpo-40275: Use new test.support helper submodules in tests

[shihai1991]

Use test helpers in the following test cases:

• test_asyncio
• test_getopt
• test_tcl
• test_xmlrpc

https://bugs.python.org/issue40275

[shihai1991]

@vstinner Hi, victor. Pls take a look if you have free time.

[vstinner]

@serhiy-storchaka: Hi. Would you be available next week to have a look at what has been done recently in test/support/__init__.py in https://bugs.python.org/issue40275 before we start to convert the whole Python test suite to newer support submodules like support.os_helper? The final goal is remove aliases from support to be able to remove imports, and also to make test/support/__init__.py smaller.

[serhiy-storchaka]

I do not see a value in getting rid of the os module import. It is one of base modules, and it is used in the test launcher and in most tests, so you actually cannot get rid of importing it. It just disturbs the files history and makes the software archeology harder. Please stop.

[shihai1991]

I do not see a value in getting rid of the os module import. It is one of base modules, and it is used in the test launcher and in most tests, so you actually cannot get rid of importing it. It just disturbs the files history and makes the software archeology harder. Please stop.

Thanks for your comment, serhiy. IMHO, it's not try to getting rid of the os module import but to control what exact modules we want import in ut.

[serhiy-storchaka]

They were always imported from the test.support module. And I do not see reasons to change this. It will just clutter the history and break automatic backporting.

[shihai1991]

They were always imported from the test.support module. And I do not see reasons to change this. It will just clutter the history and break automatic backporting.

some testcases like test_unix_events.py have not use test.support directly, the others need keep import test.support(MAYBE we need to split test.support continuously.

[vstinner]

@serhiy-storchaka:

I do not see a value in getting rid of the os module import. It is one of base modules, and it is used in the test launcher and in most tests, so you actually cannot get rid of importing it. It just disturbs the files history and makes the software archeology harder. Please stop.
They were always imported from the test.support module. And I do not see reasons to change this. It will just clutter the history and break automatic backporting.

Hi Serhiy,

The creation of the support.os_helper submodule is not directly related the "test.support has way too many imports" https://bugs.python.org/issue40275 issue, but more about the old bpo-15494 "Move test/support.py into a test.support subpackage", commit fb15aa1:

commit fb15aa1e0873043548df782ace51fe1340ea559a
Author: Nick Coghlan <ncoghlan@gmail.com>
Date:   Sun Jul 28 20:56:19 2013 +1000

    Close #15494: test.support is now a package rather than a module
    
    Initial patch by Indra Talip

Between Python 2.7 and Python 3.10, support became 2x larger:

$ wc -l 2.7/Lib/test/support/*.py
 2177 2.7/Lib/test/support/__init__.py
  170 2.7/Lib/test/support/script_helper.py
 2347 total

$ wc -l master/Lib/test/support/*.py
    41 master/Lib/test/support/bytecode_helper.py
    38 master/Lib/test/support/hashlib_helper.py
   238 master/Lib/test/support/import_helper.py
  1960 master/Lib/test/support/__init__.py
   183 master/Lib/test/support/interpreters.py
    29 master/Lib/test/support/logging_helper.py
   611 master/Lib/test/support/os_helper.py
   262 master/Lib/test/support/script_helper.py
   269 master/Lib/test/support/socket_helper.py
   204 master/Lib/test/support/testresult.py
   209 master/Lib/test/support/threading_helper.py
   180 master/Lib/test/support/warnings_helper.py
  4224 total

But this PR is not only about os_helper. There are also support.import_helper and support.warning_helper.

Removing from .import_helper import from support/init.pyremoves 9 imports fromimport test.support`:

- 'importlib',
- 'importlib._bootstrap',
- 'importlib._bootstrap_external',
- 'importlib.abc',
- 'importlib.machinery',
- 'importlib.util',
- 'typing',
- 'typing.io',
- 'typing.re',

If we remove from .warnings_helper import ... from support/__init__.py and top-level import warnings in unittest, it becomes possible to completely avoid importing warnings on import test.support.

They were always imported from the test.support module. And I do not see reasons to change this. It will just clutter the history and break automatic backporting.

If these changes create too many merge conflicts, we can backport https://bugs.python.org/issue40275 changes to 3.8 and 3.9 branches.

[vstinner]

@shihai1991: Can you please solve the merge conflict?

[shihai1991]

@shihai1991: Can you please solve the merge conflict?

sure, I rebase it now ;)

[shihai1991]

thanks, victor :)