chore(eslint): update config to catch .only and .skip files (#5303)

* chore(eslint): only ignore fixture JS files

* chore(eslint): update config to catch .only and .skip files

* chore(eslint): make .skip file comment valid js

Author: wjhsf

eslint.config.mjs

@@ -12,6 +12,8 @@ import js from '@eslint/js';
 import tseslint from 'typescript-eslint';
 import gitignore from 'eslint-config-flat-gitignore';
 import vitest from '@vitest/eslint-plugin';
+import * as espree from 'espree';
+
 import { PUBLIC_PACKAGES as publicPackageData } from './scripts/shared/packages.mjs';
 // convert filepath to eslint glob
 const PUBLIC_PACKAGES = publicPackageData.map(({ path }) => `${path}/**`);
@@ -27,7 +29,7 @@ export default tseslint.config(
 
     gitignore(),
     {
-        ignores: ['**/fixtures'],
+        ignores: ['packages/**/fixtures/**/*.js'],
     },
     js.configs.recommended,
     ...tseslint.configs.recommendedTypeChecked,
@@ -403,18 +405,35 @@ export default tseslint.config(
 
     {
         // These are empty files used to help debug test fixtures
-        files: ['**/.only'],
+        files: ['**/.only', '**/.skip'],
         plugins: { '@lwc/lwc-internal': lwcInternal },
+        languageOptions: {
+            // Using the default eslint parser because typescript-eslint doesn't
+            // seem to correctly support `extraFileExtensions`
+            parser: espree,
+            parserOptions: {
+                extraFileExtensions: ['only', 'skip'],
+            },
+        },
         rules: {
             '@lwc/lwc-internal/forbidden-filename': 'error',
+            // Disable all TS rules because they complain about the parser being espree
+            ...Object.fromEntries(
+                tseslint.configs.all
+                    .flatMap((cfg) => Object.keys(cfg.rules ?? {}))
+                    .map((rule) => [rule, 'off'])
+            ),
         },
     },
     {
-        // These are empty files used to help debug test fixtures
         files: ['**/.skip'],
-        plugins: { '@lwc/lwc-internal': lwcInternal },
         rules: {
-            '@lwc/lwc-internal/forbidden-filename': 'off',
+            // We want to avoid accidentally committing .skip files, but sometimes there are
+            // legitimate reasons to do so. So we complain when trying to commit, but not any
+            // other time.
+            '@lwc/lwc-internal/forbidden-filename':
+                // eslint-disable-next-line no-undef
+                process.env.npm_lifecycle_event === 'lint-staged' ? 'error' : 'off',
         },
     }
 );

package.json

@@ -76,11 +76,10 @@
         "vitest": "^3.0.8"
     },
     "lint-staged": {
-        "*.{js,mjs,ts}": "eslint --cache",
+        "*.{js,mjs,ts,only,skip}": "eslint --cache",
         "*.{css,js,json,md,mjs,ts,yaml,yml}": "prettier --check",
         "{packages/**/package.json,scripts/tasks/check-and-rewrite-package-json.js}": "node ./scripts/tasks/check-and-rewrite-package-json.js --test",
-        "{LICENSE-CORE.md,**/LICENSE.md,yarn.lock,scripts/tasks/generate-license-files.js,scripts/shared/bundled-dependencies.js}": "node ./scripts/tasks/generate-license-files.js --test",
-        "*.{only,skip}": "eslint --cache --plugin '@lwc/eslint-plugin-lwc-internal' --rule '@lwc/lwc-internal/forbidden-filename: error'"
+        "{LICENSE-CORE.md,**/LICENSE.md,yarn.lock,scripts/tasks/generate-license-files.js,scripts/shared/bundled-dependencies.js}": "node ./scripts/tasks/generate-license-files.js --test"
     },
     "workspaces": [
         "packages/@lwc/*",

packages/@lwc/engine-server/src/__tests__/fixtures/scope-token/.skip

@@ -1,3 +1,3 @@
-W-17972327
+// W-17972327
 
-This test fails in CI and has been doing so intermittently in recent PRs. Unfortunately, it has been difficult to reproduce and resolve when running locally. Since the failure is unrelated to this PR, we're disabling the test and have filed a work item (reference above) to investigate separately.
+// This test fails in CI and has been doing so intermittently in recent PRs. Unfortunately, it has been difficult to reproduce and resolve when running locally. Since the failure is unrelated to this PR, we're disabling the test and have filed a work item (reference above) to investigate separately.

packages/@lwc/rollup-plugin/src/__tests__/resolver/fixtures/inherited-templates/src/typescript.ts

@@ -1 +1,2 @@
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
 import Extension from 'x/ext-ts';