feat!: Support `basePath` property in config objects #223

mdjermanovic · 2025-06-08T18:44:53Z

Prerequisites checklist

I have read the contributing guidelines.

What is the purpose of this pull request?

Implements https://github.com/eslint/rfcs/tree/main/designs/2025-base-path-in-config-objects in @eslint/config-array and @eslint/config-helpers.

What changes did you make? (Give an overview)

This PR adds support for basePath property in config objects.

Marked as a breaking change for this package for two reasons:

basePath can no longer be used as a custom property.
get ignores now returns an array of objects instead of an array of ignore patterns.

Related Issues

eslint/rfcs#131

eslint/eslint#18948

Is there anything you'd like reviewers to focus on?

WIP. The proof of concept worked well with ESLint, as it always sends filenames as absolute paths. Accepting relative paths makes this a bit more complicated.

nzakas

Overall LGTM. Left one note about a slight refactor.

Would like @fasttime to review before merging.

nzakas · 2025-06-19T15:33:49Z

packages/config-array/src/config-array.js

@@ -307,6 +317,17 @@ function normalizeConfigPatterns(config) {

 	const newConfig = { ...config };

+	if (typeof config.basePath === "string") {


Looks like we have this same check on line 297? Maybe an opportunity to store in a variable?

Updated in 92a98b1

fasttime

Just a couple of suggestions, otherwise LGTM.

fasttime · 2025-06-24T09:14:23Z

packages/config-array/src/config-array.js

+		if (path.isAbsolute(config.basePath)) {
+			newConfig.basePath = path.toNamespacedPath(config.basePath);
+		} else {
+			newConfig.basePath = path.resolve(
+				namespacedBasePath,
+				config.basePath,
+			);
+		}


I think this could be simplified to remove the check with path.isAbsolute, which path.resolve should already include. From https://nodejs.org/api/path.html#pathresolvepaths:

The given sequence of paths is processed from right to left, with each subsequent path prepended until an absolute path is constructed. For instance, given the sequence of path segments: /foo, /bar, baz, calling path.resolve('/foo', '/bar', 'baz') would return /bar/baz because 'baz' is not an absolute path but '/bar' + '/' + 'baz' is.

Suggested change

if (path.isAbsolute(config.basePath)) {

newConfig.basePath = path.toNamespacedPath(config.basePath);

} else {

newConfig.basePath = path.resolve(

namespacedBasePath,

config.basePath,

);

}

newConfig.basePath = path.resolve(

namespacedBasePath,

config.basePath,

);

Absolute paths wouldn't be converted to namespaced paths, and several tests would fail (on Windows):

1) ConfigArray Config objects `basePath` normalization should create a new object with namespaced `basePath` when normalizing absolute `basePath` on windows (async): AssertionError [ERR_ASSERTION]: Expected values to be strictly deep-equal: + actual - expected { + basePath: 'C:\\foo', - basePath: '\\\\?\\C:\\foo', defs: { 'test-def': 'test-value' } } + expected - actual { - "basePath": "C:\\foo" + "basePath": "\\\\?\\C:\\foo" "defs": { "test-def": "test-value" } } at Context.<anonymous> (file:///C:/projects/rewrite/packages/config-array/tests/config-array.test.js:827:11) 2) ConfigArray Config objects `basePath` normalization should create a new object with namespaced `basePath` when normalizing absolute `basePath` on windows (sync): AssertionError [ERR_ASSERTION]: Expected values to be strictly deep-equal: + actual - expected { + basePath: 'C:\\foo', - basePath: '\\\\?\\C:\\foo', defs: { 'test-def': 'test-value' } } + expected - actual { - "basePath": "C:\\foo" + "basePath": "\\\\?\\C:\\foo" "defs": { "test-def": "test-value" } } at Context.<anonymous> (file:///C:/projects/rewrite/packages/config-array/tests/config-array.test.js:851:11) at process.processImmediate (node:internal/timers:491:21) 3) ConfigArray ConfigArray members getConfigWithStatus() should return config without meta fields `name`, `basePath`, `files`, and `ignores`: AssertionError [ERR_ASSERTION]: Expected values to be strictly deep-equal: + actual - expected { + status: 'unconfigured' - config: { - defs: { - 'test-def': 'test-value' - } - }, - status: 'matched' } + expected - actual { - "status": "unconfigured" + "config": { + "defs": { + "test-def": "test-value" + } + } + "status": "matched" } at Context.<anonymous> (file:///C:/projects/rewrite/packages/config-array/tests/config-array.test.js:1034:12) at process.processImmediate (node:internal/timers:491:21) 4) ConfigArray ConfigArray members isFileIgnored() config objects with `basePath` property should intepret `ignores` as relative to the config's `basePath` when ignoring directories (relative paths): AssertionError [ERR_ASSERTION]: Expected values to be strictly equal: true !== false + expected - actual -true +false at Context.<anonymous> (file:///C:/projects/rewrite/packages/config-array/tests/config-array.test.js:4115:13) at process.processImmediate (node:internal/timers:491:21) 5) ConfigArray ConfigArray members isFileIgnored() config objects with `basePath` property should intepret `ignores` as relative to the config's `basePath` when ignoring directories (absolute paths): AssertionError [ERR_ASSERTION]: Expected values to be strictly equal: true !== false + expected - actual -true +false at Context.<anonymous> (file:///C:/projects/rewrite/packages/config-array/tests/config-array.test.js:4302:13) at process.processImmediate (node:internal/timers:491:21) 6) ConfigArray ConfigArray members isFileIgnored() config objects with `basePath` property should intepret `ignores` as relative to the config's `basePath` when ignoring files (relative paths): AssertionError [ERR_ASSERTION]: Expected values to be strictly equal: true !== false + expected - actual -true +false at Context.<anonymous> (file:///C:/projects/rewrite/packages/config-array/tests/config-array.test.js:4593:13) at process.processImmediate (node:internal/timers:491:21) 7) ConfigArray ConfigArray members isFileIgnored() config objects with `basePath` property should intepret `ignores` as relative to the config's `basePath` when ignoring files (absolute paths): AssertionError [ERR_ASSERTION]: Expected values to be strictly equal: true !== false + expected - actual -true +false at Context.<anonymous> (file:///C:/projects/rewrite/packages/config-array/tests/config-array.test.js:4823:13) at process.processImmediate (node:internal/timers:491:21) 8) ConfigArray ConfigArray members isDirectoryIgnored() config objects with `basePath` property should intepret `ignores` as relative to the config's `basePath` (relative paths): AssertionError [ERR_ASSERTION]: Expected values to be strictly equal: true !== false + expected - actual -true +false at Context.<anonymous> (file:///C:/projects/rewrite/packages/config-array/tests/config-array.test.js:5700:13) at process.processImmediate (node:internal/timers:491:21) 9) ConfigArray ConfigArray members isDirectoryIgnored() config objects with `basePath` property should intepret `ignores` as relative to the config's `basePath` (absolute paths): AssertionError [ERR_ASSERTION]: Expected values to be strictly equal: true !== false + expected - actual -true +false at Context.<anonymous> (file:///C:/projects/rewrite/packages/config-array/tests/config-array.test.js:5865:13) at process.processImmediate (node:internal/timers:491:21)

You're right. It guess I was running the wrong tests when I checked this.

fasttime · 2025-06-24T10:15:24Z

packages/config-array/README.md

Shall we add basePath to the list of properties not included in the object returned by getConfig()?

rewrite/packages/config-array/README.md

Line 297 in 92a98b1

- The returned config object never has `files`, `ignores`, or `name` properties; the only properties on the object will be the other configuration options specified.

Updated in 82d07fd.

fasttime

LGTM, thanks!

mdjermanovic added 3 commits June 8, 2025 14:41

feat!: Support basePath` property in config objects

c9e0845

refactor matching non-global ignores

36be478

add tests for getConfigStatus

56fcb7e

github-project-automation bot added this to Triage Jun 8, 2025

github-project-automation bot moved this to Needs Triage in Triage Jun 8, 2025

eslint-github-bot bot added breaking feature labels Jun 8, 2025

mdjermanovic added 4 commits June 11, 2025 09:22

handle relative filePath input

4ef985b

no trailing slashes

941d2f1

add tests for get ignores

c9e5996

add tests for isDirectoryIgnored

665097c

JoshuaKGoldberg mentioned this pull request Jun 17, 2025

🧹 Versioning: Bump minimum Node.js version from 18.18.0 to 20.19.0 mochajs/mocha#5358

Open

add tests for isFileIgnored with ignored directories

4861c71

nzakas moved this from Needs Triage to Implementing in Triage Jun 18, 2025

mdjermanovic added 4 commits June 18, 2025 18:23

add tests for isFileIgnored with ignored files

8994966

update docs

96f2f17

add tests for defineConfig()

2c30cac

fix unwanted global ignores in defineConfig()

bd5fe68

mdjermanovic added the accepted label Jun 18, 2025

mdjermanovic marked this pull request as ready for review June 18, 2025 18:10

nzakas previously approved these changes Jun 19, 2025

View reviewed changes

refactor

92a98b1

mdjermanovic dismissed nzakas’s stale review via 92a98b1 June 19, 2025 18:23

nzakas previously approved these changes Jun 20, 2025

View reviewed changes

mdjermanovic mentioned this pull request Jun 22, 2025

feat: Support basePath property in config objects eslint/eslint#19879

Merged

1 task

fasttime reviewed Jun 24, 2025

View reviewed changes

update README

82d07fd

mdjermanovic dismissed nzakas’s stale review via 82d07fd June 24, 2025 13:32

fasttime approved these changes Jun 25, 2025

View reviewed changes

fasttime merged commit 40d31ba into main Jun 25, 2025
21 checks passed

fasttime deleted the rfc131 branch June 25, 2025 08:10

github-project-automation bot moved this from Implementing to Complete in Triage Jun 25, 2025

github-actions bot mentioned this pull request Jun 23, 2025

chore: release main #229

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feat!: Support `basePath` property in config objects #223

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		@@ -307,6 +317,17 @@ function normalizeConfigPatterns(config) {

		const newConfig = { ...config };

		if (typeof config.basePath === "string") {

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feat!: Support basePath property in config objects #223

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What is the purpose of this pull request?

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feat!: Support `basePath` property in config objects #223

feat!: Support `basePath` property in config objects #223

mdjermanovic commented Jun 8, 2025 •

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