fix(eslint-plugin): [prefer-find] support ternary branches in prefer-find

[kirkwaiblinger]

PR Checklist

• Addresses an existing open issue: fixes Bug: [prefer-find] Add support for checking ternaries #8379
• That issue was marked as accepting prs
• Steps in Contributing were taken

Overview

Adds support for recursively checking ternary branches.

[typescript-eslint]

Thanks for the PR, @kirkwaiblinger!

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The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

Thanks again!

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.06%. Comparing base (9c94b81) to head (9e599c0).
Report is 63 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8421      +/-   ##
==========================================
+ Coverage   86.94%   87.06%   +0.11%     
==========================================
  Files         252      251       -1     
  Lines       12251    12278      +27     
  Branches     3861     3870       +9     
==========================================
+ Hits        10652    10690      +38     
+ Misses       1332     1316      -16     
- Partials      267      272       +5     

Flag	Coverage Δ
unittest	87.06% <100.00%> (+0.11%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
packages/eslint-plugin/src/rules/prefer-find.ts	100.00% <100.00%> (ø)

... and 17 files with indirect coverage changes

[JoshuaKGoldberg]

Code changes look great, nicely done! 👏

Just requesting changes on a bit more testing.

[JoshuaKGoldberg]

[Testing] Just to be through, could you also add a test for a desired report with and within a ternary? Like the valid case above, but either with two .filters or with the [0] on the other side of the last )?

(Math.random() < 0.5
  ? [1, 2, 3].filter(x => false)
  : [1, 2, 3].filter(x => true))[0];

(Math.random() < 0.5
  ? [1, 2, 3].find(x => true)
  : [1, 2, 3].filter(x => true)[0]);

The cases lower down are a bit more complex. It's nice to have more straightforward ones to use as a reference too.

[JoshuaKGoldberg]

[Testing] Nit: here and below, if there's no need to use an any, might as well avoid it:

Suggested change

	declare const f: any, g: any;
	declare const f: unknown, g: unknown;

[kirkwaiblinger]

it would have a type error without. I was just too lazy to write out the actual type of the filter callback (and the rule doesn't care about the type of the filter callback) so i went for the easiest way to not error :)

[JoshuaKGoldberg]

Ha, gotcha. #8298 -> #8351 tracks making tests error on type unhappiness. cc @auvred - do you think we should start asking folks to try to not have type errors?

[auvred]

Personally, I'm +1 to avoid semantic errors, at least in newly added tests :)

Especially when it's not that hard:

- declare const f: any, g: any;
+ declare const f: (x: unknown) => boolean, g: (x: unknown) => boolean;

[kirkwaiblinger]

Fair enough, changed

[JoshuaKGoldberg]

LGTM, nice! Since it's tricky logic being touched, will leave open for a bit under 1 approval.

[auvred]

LGTM 🚀

[auvred]

LGTM! Thanks for updating tests!