Fix: Warn for deprecation in Node output (fixes #7443)

[calling]

What is the purpose of this pull request? (put an "X" next to item)

[ ] Documentation update
[x] Bug fix (template)
[ ] New rule (template)
[ ] Changes an existing rule (template)
[ ] Add autofixing to a rule
[ ] Add a CLI option
[ ] Add something to the core
[ ] Other, please explain:

#7443

What changes did you make? (Give an overview)
Added a property usedDeprecatedRules to the output of the Node API that flags usage of deprecated rules.

Is there anything you'd like reviewers to focus on?
The issue touched on other possible work (i.e. formatter changes, usedRemovedRules, usedNotFoundRules). From reading the issue, I think the group settled on only implementing usedDeprecatedRules, but please check my understanding.

[kaicataldo]

Thanks for contributing!

The code here LGTM, but I wanted to ask about the additional properties mentioned in the implementation described in this comment (usedRemovedRules and usedNotFoundRules). Did we decide not to implement those? Regardless, I'd be fine with merging this as is and adding the other two properties in a follow up PR, if we decide those would still be nice to have.

[kaicataldo]

I know this isn't a terribly complex function, but I wonder if we could reduce the complexity a bit by restructuring it as:

const ruleWarnings = { usedDeprecatedRules: [] };

if (rules) {
    Object.keys(rules).forEach(name => {
        const loadedRule = loadedRules.get(name);

         if (loadedRule.meta && loadedRule.meta.deprecated) {
            ruleWarnings.usedDeprecatedRules.push({ ruleId: name, replacedBy: loadedRule.meta.docs.replacedBy });
        }
    });
}

return ruleWarnings;

[calling]

No problem!

[platinumazure]

LGTM, thanks for contributing!

[calling]

@kaicataldo I'm also unsure the outcome of the discussion w.r.t. those other two properties (usedRemovedRules and usedNotFoundRules). Perhaps we can address that as a follow up?

[not-an-aardvark]

Thanks for the PR! I left a few minor suggestions, but overall this approach seems good to me.

[not-an-aardvark]

Will this work correctly if a rule doesn't have a meta.docs property (e.g. a rule from a plugin)?

More generally, I'm wondering if we should move meta.docs.replacedBy to just meta.replacedBy, since the replacedBy field doesn't really relate to documentation in this context. (I know it's currently meta.docs.replacedBy on existing core rules, but it's easier to change that now than later since it's not a public API yet.)

edit: In either case, I think we should also update the Working with Rules page to note the new available options in the rule API.

[calling]

That's a great point about meta.docs not necessarily existing. The "Working with Rules" page explicitly says that meta.docs is optional for custom rules and plugins: "In a custom rule or plugin, you can omit docs or include any properties that you need in it".

I'm happy to move replacedBy up to meta or I can add a property check (and document it either way), but I think where replacedBy should hang is best decided by the maintainers?

[not-an-aardvark]

My personal preference would be to move it to meta.replacedBy rather than meta.docs.replacedBy, but let's see what other team members think.

cc @kaicataldo @platinumazure

[kaicataldo]

Moving replacedBy to meta.replacedBy makes sense to me 👍

[not-an-aardvark]

Could you be more specific in this documentation about what the shape of an object in usedDeprecatedRules would look like (namely, that it has a ruleId and replacedBy property)?

[not-an-aardvark]

I think we should only include the replacedBy key if it's a string, and omit it otherwise. If a rule from a plugin does something weird and uses a different type of object as a replacedBy value, it could have the effect of crashing an integration/formatter.

[not-an-aardvark]

Regarding usedRemovedRules, I think it's probably not worth adding special logic for removed rules because we no longer remove any rules and it's been a long time since we removed any rules, so it seems unlikely that many users are still enabling removed rules. At some point it might be a good idea for us to get rid of the remaining "removed rule" logic and just treat removed rules the same way as nonexistent rules, although that doesn't need to be decided here.

[nzakas]

@not-an-aardvark it looks like your changes may have been addressed. Can you take another look?

[platinumazure]

I agree it would be nice to move to meta.replacedBy, and agree it should be done sooner than later if we're going to do it; but this is a slight preference, not a strong preference.

[calling]

Seems like the enough folks want meta.docs.replacedBy moved to meta.replacedBy, so I've moved it.

[kaicataldo]

LGTM. Thanks for contributing!

[nzakas]

@not-an-aardvark looks like we just need an approval from you to move this forward. Can you take another look?

[not-an-aardvark]

LGTM, thanks!

[nzakas]

Merged, thanks for the contribution. This will be super helpful to users.