chore: add no-unused-expressions lint rule #7007

simon-id · 2025-11-27T13:30:08Z

What does this PR do?

Add the eslint rule no-unused-expressions, it prevents stuff like:

function a () {
  if (x) false // forgot the return statement

  blabla()
}

It also allows the use of the void operator, to explicitly allow statements with only side effects.

Motivation

Mistakes have been made in previous PRs that could have been prevented with this rule.

github-actions · 2025-11-27T13:30:27Z

Overall package size

Self size: 13.41 MB
Deduped: 113.61 MB
No deduping: 128.63 MB

Dependency sizes

| name | version | self size | total size | |------|---------|-----------|------------| | @datadog/libdatadog | 0.7.0 | 35.02 MB | 35.02 MB | | @datadog/native-appsec | 10.3.0 | 20.73 MB | 20.74 MB | | @datadog/pprof | 5.12.0 | 11.19 MB | 11.57 MB | | @datadog/native-iast-taint-tracking | 4.1.0 | 9.01 MB | 9.02 MB | | @opentelemetry/resources | 1.30.1 | 557.67 kB | 7.71 MB | | @opentelemetry/core | 1.30.1 | 908.66 kB | 7.16 MB | | protobufjs | 7.5.4 | 2.95 MB | 5.83 MB | | @datadog/wasm-js-rewriter | 5.0.1 | 2.82 MB | 3.53 MB | | @datadog/native-metrics | 3.1.1 | 1.02 MB | 1.43 MB | | @opentelemetry/api-logs | 0.208.0 | 199.48 kB | 1.42 MB | | @opentelemetry/api | 1.9.0 | 1.22 MB | 1.22 MB | | jsonpath-plus | 10.3.0 | 617.18 kB | 1.08 MB | | import-in-the-middle | 1.15.0 | 127.66 kB | 856.24 kB | | lru-cache | 10.4.3 | 804.3 kB | 804.3 kB | | @datadog/openfeature-node-server | 0.2.0 | 118.51 kB | 437.19 kB | | opentracing | 0.14.7 | 194.81 kB | 194.81 kB | | source-map | 0.7.6 | 185.63 kB | 185.63 kB | | pprof-format | 2.2.1 | 163.06 kB | 163.06 kB | | @datadog/sketches-js | 2.1.1 | 109.9 kB | 109.9 kB | | @isaacs/ttlcache | 2.1.2 | 90.79 kB | 90.79 kB | | lodash.sortby | 4.7.0 | 75.76 kB | 75.76 kB | | ignore | 7.0.5 | 63.38 kB | 63.38 kB | | istanbul-lib-coverage | 3.2.2 | 34.37 kB | 34.37 kB | | rfdc | 1.4.1 | 27.15 kB | 27.15 kB | | dc-polyfill | 0.1.10 | 26.73 kB | 26.73 kB | | tlhunter-sorted-set | 0.1.0 | 24.94 kB | 24.94 kB | | shell-quote | 1.8.3 | 23.74 kB | 23.74 kB | | limiter | 1.1.5 | 23.17 kB | 23.17 kB | | retry | 0.13.1 | 18.85 kB | 18.85 kB | | semifies | 1.0.0 | 15.84 kB | 15.84 kB | | jest-docblock | 29.7.0 | 8.99 kB | 12.76 kB | | crypto-randomuuid | 1.0.0 | 11.18 kB | 11.18 kB | | ttl-set | 1.0.0 | 4.61 kB | 9.69 kB | | mutexify | 1.4.0 | 5.71 kB | 8.74 kB | | path-to-regexp | 0.1.12 | 6.6 kB | 6.6 kB | | module-details-from-path | 1.0.4 | 3.96 kB | 3.96 kB | | escape-string-regexp | 5.0.0 | 3.66 kB | 3.66 kB |

_{🤖 This report was automatically generated by heaviest-objects-in-the-universe}

codecov · 2025-11-27T13:30:48Z

Codecov Report

❌ Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 84.94%. Comparing base (0bb1f17) to head (5782f36).

Files with missing lines	Patch %	Lines
packages/datadog-instrumentations/src/dns.js	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #7007   +/-   ##
=======================================
  Coverage   84.94%   84.94%           
=======================================
  Files         514      514           
  Lines       21754    21754           
=======================================
  Hits        18478    18478           
  Misses       3276     3276

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

pr-commenter · 2025-11-27T13:39:13Z

Benchmarks

Benchmark execution time: 2025-12-01 18:50:46

Comparing candidate commit 5782f36 in PR branch simon-id-patch-2 with baseline commit 0bb1f17 in branch master.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 288 metrics, 32 unstable metrics.

datadog-official · 2025-12-01T16:46:37Z

⚠️ Tests

⚠️ Warnings

❄️ 3 New flaky tests detected

express-mongo-sanitize with express-mongo-sanitize >=1.0.0 (1.0.0) middleware without subscriptions it continues working with sanitization request from without subscriptions (Datadog)
Expected values to be strictly equal:
+ actual - expected

+ 'paramvalue'
- undefined

AssertionError [ERR_ASSERTION]: Expected values to be strictly equal:
+ actual - expected

+ 'paramvalue'
...
express-mongo-sanitize with express-mongo-sanitize >=1.0.0 (1.0.0) middleware with subscriptions it continues working with sanitization request from with subscriptions (Datadog)
Expected values to be strictly equal:
+ actual - expected

+ 'paramvalue'
- undefined

AssertionError [ERR_ASSERTION]: Expected values to be strictly equal:
+ actual - expected

+ 'paramvalue'
...
express-mongo-sanitize with express-mongo-sanitize >=1.0.0 (1.0.0) middleware with subscriptions subscription is called with expected parameters with sanitization request from with subscriptions (Datadog)
Expected values to be strictly equal:
+ actual - expected

+ 'paramvalue'
- undefined

AssertionError [ERR_ASSERTION]: Expected values to be strictly equal:
+ actual - expected

+ 'paramvalue'
...

ℹ️ Info

🧪 All tests passed

_{This comment will be updated automatically if new data arrives.

🔗 Commit SHA: 5782f36 | Docs | Datadog PR Page | Was this helpful? Give us feedback!}

simon-id · 2025-12-02T12:42:21Z

packages/datadog-instrumentations/src/mariadb.js

          return result
        }, error => {
-          ctx.error
+          ctx.error = error


@rochdev need your approval on this, the change i made is only a guess

This looks like a bug fix. Could you please add a test for that?

yes, but i'll let roch do this, because i don't even know what bug this fixes

BridgeAR · 2025-12-02T17:02:30Z

eslint.config.mjs

      'no-implicit-coercion': ['error', { boolean: true, number: true, string: true, allow: ['!!'] }],
+      'no-unused-expressions': 'error',
      'no-useless-assignment': 'error',
+      'no-void': 'off',


I think it is better to use the eslint exception for accessing the stack, while I am uncertain if accessing it is still needed at all. There were some V8 changes that might make that obsolete (I did not check).

any reasoning against void ? just picked that because i never remember the eslint exception syntax, void is easy to remember

BridgeAR · 2025-12-02T17:04:08Z

packages/datadog-plugin-azure-functions/src/index.js

      return tracer.extract('http_headers', Object.fromEntries(ctx.httpRequest.headers))
    default:
-      null
+      return null


AFAIK it's even possible to just remove the default which would allow this to be a simple if statement. While being on this: the String() call is not needed.

Of course the default here is not needed if the caller accept undefined instead of null, but i'm trying to keep the changes as iso as possible, this is just a linter PR, if i stop at every little thing that can be improved, the PR will be very off topic

I thought it was unnecessary when i saw it too, but if i go and change it, i run the risk of creating more problems and failing tests and stuff, that i'm not interested in investing time on now. Especially since I'm making this PR completely online without running it locally, so iteration time is way slower. Small PR for a small task

BridgeAR · 2025-12-02T17:04:34Z

packages/datadog-instrumentations/src/mariadb.js

          return result
        }, error => {
-          ctx.error
+          ctx.error = error


This looks like a bug fix. Could you please add a test for that?

Update eslint.config.mjs

aede19c

zeui

42e153b

simon-id added the semver-patch label Dec 1, 2025

simon-id added 5 commits December 1, 2025 17:26

add void before error.stack

1ec0138

replace short-circuit with optional chaining

41f60e0

replace short-circuit with if condition

4586202

add probably missing return

c851f95

order rule correctly

7ab17ec

simon-id changed the title ~~Update eslint.config.mjs~~ chore: add no-unused-expressions lint rule Dec 1, 2025

Merge branch 'master' into simon-id-patch-2

2182259

simon-id self-assigned this Dec 1, 2025

simon-id added 2 commits December 1, 2025 19:31

disable no-void

511df85

fix weird line

5782f36

simon-id marked this pull request as ready for review December 2, 2025 12:41

simon-id requested review from a team as code owners December 2, 2025 12:41

simon-id requested review from khanayan123 and removed request for a team December 2, 2025 12:41

simon-id commented Dec 2, 2025

View reviewed changes

BridgeAR reviewed Dec 2, 2025

View reviewed changes

rochdev approved these changes Dec 2, 2025

View reviewed changes

chore: add no-unused-expressions lint rule #7007

Are you sure you want to change the base?

chore: add no-unused-expressions lint rule #7007

Conversation

simon-id commented Nov 27, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

What does this PR do?

Motivation

Uh oh!

github-actions bot commented Nov 27, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Overall package size

Uh oh!

codecov bot commented Nov 27, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Codecov Report

Uh oh!

pr-commenter bot commented Nov 27, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Benchmarks

Uh oh!

datadog-official bot commented Dec 1, 2025 • edited by datadog-datadog-prod-us1 bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

⚠️ Warnings

ℹ️ Info

Uh oh!

simon-id Dec 2, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

4 participants

simon-id commented Nov 27, 2025 •

edited

Loading

github-actions bot commented Nov 27, 2025 •

edited

Loading

codecov bot commented Nov 27, 2025 •

edited

Loading

pr-commenter bot commented Nov 27, 2025 •

edited

Loading

datadog-official bot commented Dec 1, 2025 •

edited by datadog-datadog-prod-us1 bot

Loading

simon-id Dec 2, 2025 •

edited

Loading