Move B042 to B913 to not be enabled by deefault due to false positives

[cooperlees]

• Some false positives we need to iron out
• Until someone wants to do that, let's not enable this check by default by moving to a B9XX
• I've reserved B042 incase we want to ever move it back

Test:

• Move tests and see them stay passing as is

python3 -m venv --upgrade-dep /tmp/tf
/tmp/tf/bin/pip install tox
/tmp/tf/bin/tox -e py314
...
============================================================================================= test session starts ==============================================================================================
platform darwin -- Python 3.14.0, pytest-9.0.0, pluggy-1.6.0
cachedir: .tox/py314/.pytest_cache
rootdir: /Users/cooper/repos/flake8-bugbear
configfile: pyproject.toml
plugins: hypothesis-6.147.0
collected 76 items

tests/test_bugbear.py ............................................................................                                                                                                       [100%]

============================================================================================= 76 passed in 10.49s ==============================================================================================
py314: commands[1]> coverage report -m
Name         Stmts   Miss  Cover   Missing
------------------------------------------
bugbear.py    1116     20    98%   141-142, 152-163, 294, 308, 416, 758, 1275, 1454, 1471, 1605, 1713, 1792, 1910-1911, 2047-2048
------------------------------------------
TOTAL         1116     20    98%
  py314: OK (18.98=setup[7.08]+cmd[11.76,0.15] seconds)
  congratulations :) (19.01 seconds)

Addresses #525

[cooperlees]

Does this make more sense on how to use it? Welcome all improvements here ...

[cooperlees]

Happy to improve here too

[Copilot]

Pull Request Overview

This pull request moves the B042 check to B913, making it disabled by default. The check validates that custom exception classes with __init__ methods properly pass all arguments to super().__init__() and do not accept kwargs.

Key changes:

• Renamed the B042 error code to B913 throughout the codebase
• Moved B913 to the disabled_by_default list to make it opt-in
• Updated documentation to reflect that B042 is now reserved for future use

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
bugbear.py	Renamed check_for_b042 method to check_for_b913, updated all error references from B042 to B913, moved error definition from B042 to B913, and added B913 to disabled_by_default list
tests/eval_files/b913.py	Updated test expectations from B042 to B913 in all test case comments
README.rst	Updated B042 documentation to indicate it's reserved for future use, added B913 documentation, and updated changelog entries

Comments suppressed due to low confidence (5)

tests/eval_files/b913.py:61

• This class does not call Anything.init during initialization. (MyError.init may be missing a call to a base class init)
  tests/eval_files/b913.py:63
• This class does not call Anything.init during initialization. (MyException.init may be missing a call to a base class init)
  tests/eval_files/b913.py:65
• This class does not call Anything.init during initialization. (MyExceptionGroup.init may be missing a call to a base class init)
  tests/eval_files/b913.py:67
• This class does not call Anything.init during initialization. (MyWarning.init may be missing a call to a base class init)
  tests/eval_files/b913.py:70
• This class does not call Anything.init during initialization. (ExceptionHandler.init may be missing a call to a base class init)

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Missing period at the end of the changelog entry. Should be 'It checks for reminding to call super().init() in custom exceptions.'

Suggested change

	* B913: Move B042 to be optional by default. It checks for reminding to call super().__init__ in custom exceptions
	* B913: Move B042 to be optional by default. It checks for reminding to call super().__init__ in custom exceptions.

[cooperlees]

Seems the checks noise is not that high. Closing this and we can maybe just be a little more verbose in docs.