fix(eslint-plugin): [no-floating-promises] finally should be transparent to unhandled promises

[kirkwaiblinger]

PR Checklist

• Addresses an existing open issue: fixes Bug: [no-floating-promises] Incorrect handling of finally calls #5692
• That issue was marked as accepting prs
• Steps in Contributing were taken

Overview

The existing implementation treats .finally as though it can account for a rejected promise. It cannot prevent rejection. This PR implements the change recommended in the discussion for this issue, namely, to make .finally transparent to the rule and check whatever comes before it.

Promise.reject().finally(() => {}) // was ok, now an error
Promise.reject().catch(() => {}).finally(() => {}).finally(() => {}) // was ok - still ok

Note - this will have conflicts with #6881. It would be simpler to merge that PR first and then deal with the conflicts here.

[typescript-eslint]

Thanks for the PR, @kirkwaiblinger!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

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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✅ Successfully ran 35 targets

• nx test eslint-plugin --coverage=false
• Node 20 - nx test eslint-plugin
• Node 16 - nx test eslint-plugin --coverage=false
• nx test eslint-plugin-internal --coverage=false
• nx run types:build
• nx test typescript-estree --coverage=false
• Node 20 - nx test visitor-keys
• Node 20 - nx run types:build
• Node 20 - nx test type-utils
• Node 20 - nx test utils
• Node 20 - nx test typescript-estree
• Node 20 - nx test scope-manager
• nx test eslint-plugin-tslint --coverage=false
• Node 20 - nx test parser
• Node 20 - nx test rule-schema-to-typescript-types
• Node 20 - nx test repo-tools
• Node 20 - nx test eslint-plugin-internal
• Node 20 - nx test ast-spec
• Node 20 - nx test eslint-plugin-tslint
• Node 16 - nx test visitor-keys --coverage=false
• Node 16 - nx run types:build
• nx run-many --target=typecheck --parallel
• nx run-many --target=lint --parallel
• Node 16 - nx test utils --coverage=false
• Node 16 - nx test type-utils --coverage=false
• Node 16 - nx test typescript-estree --coverage=false
• Node 16 - nx test rule-schema-to-typescript-types --coverage=false
• Node 16 - nx test eslint-plugin-tslint --coverage=false
• Node 16 - nx test scope-manager --coverage=false
• Node 16 - nx test parser --coverage=false
• Node 16 - nx test repo-tools --coverage=false
• Node 16 - nx test eslint-plugin-internal --coverage=false
• nx run integration-tests:test
• Node 16 - nx test ast-spec --coverage=false
• nx run-many --target=build --parallel --exclude=website --exclude=website-eslint

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[codecov]

Codecov Report

Merging #7092 (6354b30) into main (a9d7bb1) will not change coverage.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7092   +/-   ##
=======================================
  Coverage   87.47%   87.47%           
=======================================
  Files         379      379           
  Lines       13230    13230           
  Branches     3906     3906           
=======================================
  Hits        11573    11573           
  Misses       1279     1279           
  Partials      378      378           

Flag	Coverage Δ
unittest	87.47% <100.00%> (ø)

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

Impacted Files	Coverage Δ
...es/eslint-plugin/src/rules/no-floating-promises.ts	100.00% <100.00%> (ø)

[JoshuaKGoldberg]

This looks great, thanks a bunch @kirkwaiblinger!

Sorry for taking so long to review 😞 we've been caught up in v6 work for a while and I'm only now getting back into the PR review queue.

Approving now, will look at the other PR too.

[JoshuaKGoldberg]

[Non-actionable] Aside: the promiseValue.finally(() => {}); on line 173 (unchanged by this PR) can be removed because that test case doesn't define a promiseValue value. It's an existing typo 😄. Not requesting any action, just noting for reference. This is good good first issue fodder.

[JoshuaKGoldberg]

[Praise] This second line was very helpful for understanding the code :) great comment!

[JoshuaKGoldberg]

Thanks, this looks great!