gh-128772: Fix - warnings.deprecated doesn't work well with pydoc

[srinivasreddy]

• Issue: warnings.deprecated doesn't work well with pydoc #128772

[terryjreedy]

The new test for the change to the warnings module belongs in test.test_warnings.

Revert this change to the idlelib file. This idle test is strictly for testing that idle reverts its monkeypatching of warnings before it exits.

[bedevere-app]

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[terryjreedy]

This probably should have a blurb and whoever merges may require one.

[serhiy-storchaka]

Is it necessary to use exec()? Can the tests simply use local classes as other deprecated() tests? Is it necessary to create an instance of the deprecated class?

[srinivasreddy]

1. bug occurs only when we run help(<module name>), in order to simulate separate module i have used exec. We cannot use classes in test cases because a class assumes __module__ of its containing test file. I am open to use other simpler approaches.
2. For the first test case CODE_SIMPLE, yes it is required to create an instance. For the second it is not required.

[serhiy-storchaka]

Since test_warnings already has been converted to a package, and there is a subpackage data, it can be easy to add a file with deprecated classes.

I can reproduce the original issue without creating an instance of the class.

[Viicos]

Alternatively, this can be fixed in pydoc, by accounting for methods without a __module__:

class A:
    def __new__(cls): pass

A.__new__.__module__ = None

# pydoc on A fails

warnings.deprecated just so happens to wrap object.__new__ which doesn't have a __module__, but the TypeError encountered in the issue can also happen in other cases.

[srinivasreddy]

@serhiy-storchaka Done. Pls review again

[serhiy-storchaka]

Alternatively, this can be fixed in pydoc, by accounting for methods without a __module__:

You are right. This is a more correct way to fix this issue.

See #129177.

[srinivasreddy]

@serhiy-storchaka Nice. Can we close this PR?