fix(eslint-plugin): [strict-boolean-expression] false positive for truthy boolean

[lonyele]

PR Checklist

• Addresses an existing issue: fixes [strict-boolean-expressions] False positive for "true | undefined" #4103
• That issue was marked as accepting prs
• Steps in CONTRIBUTING.md were taken

Overview

I checked the return value type from ts.TypeChecker and found that a value from a simple situation like boolean, true, false has distinguishable intrinsicName 'boolean'/'true'/'false', but more complicated union type situation needs the process of tsutils.unionTypeParts(type) which makes boolean type object divided into 2 seperate object with 'true' and 'false' which made me to check booleans length for checking truthy boolean

const type = util.getConstrainedTypeAtLocation(typeChecker, tsNode);
const types = inspectVariantTypes(tsutils.unionTypeParts(type));

[typescript-eslint]

Thanks for the PR, @lonyele!

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!

---

🙏 Please, if you or your company is finding typescript-eslint valuable, help us sustain the project by sponsoring it transparently on https://opencollective.com/typescript-eslint. As a thank you, your profile/company logo will be added to our main README which receives thousands of unique visitors per day.

[netlify]

❌ Deploy Preview for typescript-eslint failed.

🔨 Explore the source changes: 384f528

🔍 Inspect the deploy log: https://app.netlify.com/sites/typescript-eslint/deploys/61b04cfb50bdce000834c0cd

[nx-cloud]

Nx Cloud Report

CI ran the following commands for commit 384f528. Click to see the status, the terminal output, and the build insights.

📂 See all runs for this branch

Status	Command
	Node 16.x - nx test @typescript-eslint/eslint-plugin-tslint
	Node 16.x - nx test @typescript-eslint/eslint-plugin
	Node 14.x - nx test @typescript-eslint/eslint-plugin-tslint
	Node 14.x - nx test @typescript-eslint/eslint-plugin
	Node 12.x - nx test @typescript-eslint/eslint-plugin-internal
	Node 12.x - nx test @typescript-eslint/eslint-plugin-tslint
	Node 12.x - nx test @typescript-eslint/eslint-plugin
	Node 12.x - nx test @typescript-eslint/eslint-plugin-tslint
	Node 12.x - nx test @typescript-eslint/eslint-plugin
	Node 12.x - nx run-many --target=typecheck --all --parallel
	Node 14.x - nx test @typescript-eslint/parser
	Node 14.x - nx test @typescript-eslint/experimental-utils
	Node 14.x - nx test @typescript-eslint/scope-manager

---

Sent with 💌 from NxCloud.

[codecov]

Codecov Report

Merging #4275 (384f528) into main (9c22f65) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #4275   +/-   ##
=======================================
  Coverage   93.37%   93.37%           
=======================================
  Files         152      152           
  Lines        8085     8090    +5     
  Branches     2596     2599    +3     
=======================================
+ Hits         7549     7554    +5     
  Misses        181      181           
  Partials      355      355           

Flag	Coverage Δ
unittest	93.37% <100.00%> (+<0.01%)	⬆️

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

Impacted Files	Coverage Δ
...int-plugin/src/rules/strict-boolean-expressions.ts	98.81% <100.00%> (+0.03%)	⬆️

[bradzacher]

LGTM - thanks for this!