tools: enable (sensible) additional eslint rules #16243

apapirovski · 2017-10-16T23:03:12Z

This PR proposes enabling some additional rules that the project either already follows or probably should follow. Here’s the full overview:

no-lonely-if

If an if statement is the only statement in the else block, it is often clearer to use an else if form.

This one required some fix ups in existing code but IMO it's a good rule to have. Often these end up being a result of refactoring where the maintainer doesn't spot that the inner conditional block can be pulled out into an else if. (I personally had this come up on a recent PR.)

https://eslint.org/docs/rules/no-lonely-if

for-direction

for loop with a stop condition that can never be reached, such as one with a counter that moves in the wrong direction, will run infinitely. While there are occasions when an infinite loop is intended, the convention is to construct such loops as while loops. More typically, an infinite for loop is a bug.

I don't think this is particularly controversial. If someone tries to write code that does go against this rule they should probably refactor or it'll be hard/impossible to follow in the future.

https://eslint.org/docs/rules/for-direction

accessor-pairs

It’s a common mistake in JavaScript to create an object with just a setter for a property but never have a corresponding getter defined for it. Without a getter, you cannot read the property, so it ends up not being used.

Again, not something that's an issue currently and if someone does do this, it's very likely an error or they should just go ahead and override.

https://eslint.org/docs/rules/accessor-pairs

symbol-description

This rule requires a description when creating symbols

This one is only enabled for lib since I don't think we particularly care about this for doc or test. We already follow it but will be good to have for any potential future contributors.

https://eslint.org/docs/rules/symbol-description

(Side-note: is this tools, build or something else? Had no clue what to label the commit with.)

Checklist

make -j4 test (UNIX), or vcbuild test (Windows) passes
commit message follows commit guidelines

Affected core subsystem(s)

doc, lib, test, tools

vsemozhetbyt · 2017-10-16T23:25:50Z

test/parallel/test-util-inspect.js

@@ -1149,3 +1151,4 @@ if (typeof Symbol !== 'undefined') {
 }

 assert.doesNotThrow(() => util.inspect(process));
+/* eslint-enable accessor-pairs */


I am not sure, but this line seems not needed since there is no code left for linting.

Yeah, that was my thinking but I've noticed a bunch of our test files do this so I just followed the convention.

Oh, maybe this is some over-caution for possible future code addition?

Possibly. If someone does know, I would love to know the reason. Or maybe we're all just following the lead of the first person that did this... 😂

I think the main reason is to try to limit the deactivation for any rule to the minimum required lines.

Yes, in many tests such enabling comments are inserted in the middle of the code. But as the last line, they may be a bit confusing. However, they can have the same role as trailing commas in arrays and objects: safety device for future additions.

vsemozhetbyt · 2017-10-16T23:28:14Z

A memo for a lander: all the commits may need to be squashed before landing to be self-sufficing.

vsemozhetbyt · 2017-10-16T23:32:17Z

CI: https://ci.nodejs.org/job/node-test-pull-request/10768/

refack · 2017-10-16T23:37:23Z

test/parallel/test-util-inspect.js

@@ -26,6 +26,8 @@ const JSStream = process.binding('js_stream').JSStream;
 const util = require('util');
 const vm = require('vm');

+/* eslint-disable accessor-pairs */


Still a good idea to comment why:

// this test uses unmatched accessors to try and trip up `inspect`

refack · 2017-10-16T23:40:02Z

(Side-note: is this tools, build or something else? Had no clue what to label the commit with.)

AFAICT we mark linting changes as tools

lpinca · 2017-10-17T07:22:14Z

lib/_stream_readable.js

+  // userland ones.  NEVER DO THIS. This is here only because this code needs
+  // to continue to work with older versions of Node.js that do not include
+  // the prependListener() method. The goal is to eventually remove this hack.
+  else if (!emitter._events || !emitter._events[event])


Nit: this could be an if instead of else if as there is a return statement in the previous if body.

Nice catch! I'll update this later today.

Funny enough, there's actually a rule I want to introduce that deals with that but it requires changing more files (around 80 total instances, can't recall how many files) so I wanted to keep it for a separate PR in case there was push back.

Force pushed to address this.

May be a case for Code And Learn (nodejs/code-and-learn#72 (comment))

Enable additional rules that node either already adheres to or it makes sense to do so going forward: for-direction, accessor-pairs, no-lonely-if and symbol-description. Refs: https://eslint.org/docs/rules/for-direction Refs: https://eslint.org/docs/rules/accessor-pairs Refs: https://eslint.org/docs/rules/no-lonely-if Refs: https://eslint.org/docs/rules/symbol-description

Fishrock123 · 2017-10-19T17:48:33Z

lib/url.js

@@ -128,16 +128,14 @@ Url.prototype.parse = function parse(url, parseQueryString, slashesDenoteHost) {
      if (isWs)
        continue;
      lastPos = start = i;
-    } else {


IMO this spot makes more sense without the change, fwiw

Enable additional rules that node either already adheres to or it makes sense to do so going forward: for-direction, accessor-pairs, no-lonely-if and symbol-description. Fix all instances of no-lonely-if in lib & test and disable accessor-pairs in test-util-inspect. PR-URL: nodejs#16243 Refs: https://eslint.org/docs/rules/for-direction Refs: https://eslint.org/docs/rules/accessor-pairs Refs: https://eslint.org/docs/rules/no-lonely-if Refs: https://eslint.org/docs/rules/symbol-description Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com> Reviewed-By: Refael Ackermann <refack@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

apapirovski · 2017-10-19T17:58:36Z

Landed in 3c0ebf5

Sorry, @Fishrock123 I was already done by the time I saw your note. 😓

Enable additional rules that node either already adheres to or it makes sense to do so going forward: for-direction, accessor-pairs, no-lonely-if and symbol-description. Fix all instances of no-lonely-if in lib & test and disable accessor-pairs in test-util-inspect. PR-URL: #16243 Refs: https://eslint.org/docs/rules/for-direction Refs: https://eslint.org/docs/rules/accessor-pairs Refs: https://eslint.org/docs/rules/no-lonely-if Refs: https://eslint.org/docs/rules/symbol-description Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com> Reviewed-By: Refael Ackermann <refack@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Enable additional rules that node either already adheres to or it makes sense to do so going forward: for-direction, accessor-pairs, no-lonely-if and symbol-description. Fix all instances of no-lonely-if in lib & test and disable accessor-pairs in test-util-inspect. PR-URL: nodejs/node#16243 Refs: https://eslint.org/docs/rules/for-direction Refs: https://eslint.org/docs/rules/accessor-pairs Refs: https://eslint.org/docs/rules/no-lonely-if Refs: https://eslint.org/docs/rules/symbol-description Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com> Reviewed-By: Refael Ackermann <refack@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

MylesBorins · 2017-11-16T20:45:34Z

Should this be backported to v6.x-staging? If yes please follow the guide and raise a backport PR, if not let me know or add the dont-land-on label.

This should likely come with an update to ESLint

Enable additional rules that node either already adheres to or it makes sense to do so going forward: for-direction, accessor-pairs, no-lonely-if and symbol-description. Fix all instances of no-lonely-if in lib & test and disable accessor-pairs in test-util-inspect. PR-URL: nodejs/node#16243 Refs: https://eslint.org/docs/rules/for-direction Refs: https://eslint.org/docs/rules/accessor-pairs Refs: https://eslint.org/docs/rules/no-lonely-if Refs: https://eslint.org/docs/rules/symbol-description Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de> Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com> Reviewed-By: Refael Ackermann <refack@gmail.com> Reviewed-By: James M Snell <jasnell@gmail.com> Reviewed-By: Luigi Pinca <luigipinca@gmail.com> Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test: disable accessor-pairs in test-util-inspect

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nodejs-github-bot added the lib / src Issues and PRs related to general changes in the lib or src directory. label Oct 16, 2017

vsemozhetbyt reviewed Oct 16, 2017

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refack approved these changes Oct 16, 2017

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vsemozhetbyt approved these changes Oct 16, 2017

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cjihrig approved these changes Oct 17, 2017

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lpinca approved these changes Oct 17, 2017

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apapirovski added 2 commits October 17, 2017 20:19

lib: fix eslint no-lonely-if

bda0695

apapirovski force-pushed the additional-eslint-rules branch from dfc4e66 to 99fe59e Compare October 18, 2017 00:19

vsemozhetbyt mentioned this pull request Oct 18, 2017

Code And Learn at NodeFest 2017 nodejs/code-and-learn#72

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BridgeAR approved these changes Oct 18, 2017

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jasnell approved these changes Oct 18, 2017

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Fishrock123 reviewed Oct 19, 2017

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apapirovski closed this Oct 19, 2017

apapirovski deleted the additional-eslint-rules branch October 19, 2017 18:00

MylesBorins added the backport-requested-v6.x label Nov 16, 2017

apapirovski added dont-land-on-v4.x and removed backport-requested-v6.x labels Jan 10, 2018

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tools: enable (sensible) additional eslint rules #16243

tools: enable (sensible) additional eslint rules #16243

apapirovski commented Oct 16, 2017 •

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MylesBorins commented Nov 16, 2017

tools: enable (sensible) additional eslint rules #16243

tools: enable (sensible) additional eslint rules #16243

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apapirovski commented Oct 16, 2017 • edited Loading

no-lonely-if

for-direction

accessor-pairs

symbol-description

Checklist

Affected core subsystem(s)

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vsemozhetbyt commented Oct 16, 2017 • edited Loading

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apapirovski commented Oct 19, 2017

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