Pylint part 2

[glennmatthews]

Towards: #2292

What's Changed

Trying to keep these PRs a bit more manageable. :-) This one enables a few more of the highest-severity ("Error") pylint checkers and addresses them as described:

• Enable E0203 access-member-before-definition and fix the 1 case it flagged (a minor if legitimate bug with a missing default value in UpdateObjectViewTestCase)
• Enable E1136 unsubscriptable-object, no reports for this warning (probably got fixed along the way in the time since I initially set up the pylint configs)
• Enable E1120 no-value-for-parameter; it reported a few warnings in test code due to Pylint not innately understanding how unittest.mock.patch works; fixed this by adding signature-mutators to the Pylint configuration.
• Enable E1133 not-an-iterable; 5 warnings reported, all of which appear to be false positives where we have an optional parameter defaulting to None and pylint not recognizing that we're guarding with a if parameter is not None before trying to iterate over that parameter. I added type hints to these in hopes that it would get pylint to take the hint, but it appears not, so I added explicit pylint: disable for each of these as well.
• Enhance the pylint invoke task to permit targeted execution like invoke pylint --target nautobot.utilities.testing, invoke pylint --target examples/example_plugin --recursive.

TODO

• Explanation of Change(s)
• n/a Attached Screenshots, Payload Example
• n/a Unit, Integration Tests
• n/a Documentation Updates (when adding/changing features)
• n/a Example Plugin Updates (when adding/changing features)
• n/a Outline Remaining Work, Constraints from Design

[bryanculver]

Curious of the value of keeping the type hints in here if ultimately didn't solve the lint issue.

Maybe we should do __iter__ checks instead of is not None?

Since Python doesn't do strict type enforcement at runtime maybe pylint is being overly pessimistic and wanting to see something like

if hasattr(self.relationships, '__iter__'):

[glennmatthews]

Curious of the value of keeping the type hints in here if ultimately didn't solve the lint issue.

I mean in the long run I would love to turn on mypy for type checking as well... :-)

Maybe we should do __iter__ checks instead of is not None?

Since Python doesn't do strict type enforcement at runtime maybe pylint is being overly pessimistic and wanting to see something like

if hasattr(self.relationships, '__iter__'):

I'll give it a try.

[bryanculver]

Curious of the value of keeping the type hints in here if ultimately didn't solve the lint issue.

I mean in the long run I would love to turn on mypy for type checking as well... :-)

[glennmatthews]

I tried if hasattr(..., '__iter__') and even if isinstance(..., (list, tuple)) and neither made Pylint happy as a guard around some of these not-an-iterable cases. Explicitly casting to list (for item in list(variable)) did but I am not a big fan of that approach. I was able to address a couple of the cases by tweaking the actual logic flow a bit though.

[HanlinMiao]

LGTM!