New codemod to add missing self/cls

[clavedeluna]

Overview

A codemod that checks if instance/class methods without any args need self/cls

Description

• This codemod follows the sonar rule exactly, without adding any other features other than the edge cases for __new__ and __init_subclass__ sonar mentions
• However, while working on this I thought about additional steps we could take, either in this codemod or as a separate codemod:

1. As is, we're only checking methods/class methods with no args at all. However, what about those which have args but none are self / cls?
2. As is, when a method has no args, we just add self. However, another valid change would be to make it a @staticmethod. For example:

def A(): 
	print("instance_method")
	# `self` is never used in the method, we could make this a staticmethod

def B(): 
	self.hi = 1
        # `self` is used, so this should have `self` as an arg

Right now we handle both cases the same: just add self. However, we could decide to handle for case A by checking if self is ever used. Could be a bit tricky. It is less risky to just add self than it is to incorrectly assume self is never used and making it a staticmethod.

Closes #297

[drdavella]

Looks really nice overall, just a few minor comments.

To address your points:

• I think it's okay to use the lack of @staticmethod to infer intent here, but obviously there might be a small set of cases where we'd be wrong
• Doing this when other arguments are present would be really cool but it does seem challenging. Unfortunately since self and cls are not actually keywords it becomes pretty hard to tell what was actually intended in those cases, although probably in 99% of cases our fix would be okay.

[clavedeluna]

Reviewers: note the change in implementation to correctly handle nested functions.

addressed all requested changes from Dan

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud