Bug 1846758 - Automatically mark *.worker.?js files as belonging to the worker environment. r=Gijs

Differential Revision: https://phabricator.services.mozilla.com/D185321

docs/code-quality/lint/linters/eslint.rst

@@ -20,6 +20,24 @@ ESLint also supports the ``--fix`` option to autofix most errors raised from mos
 
 See the `Usage guide`_ for more options.
 
+Custom Configurations
+---------------------
+
+Our ESLint configuration has a number of custom configurations that define
+globals and rules for various code based on the pattern file path and names.
+
+Using the correct patterns helps ESLint to know about the correct details, so
+that you don't get warnings about undefined or unused variables.
+
+* ``.mjs`` - A module file.
+* ``.sys.mjs`` - A system module, this is typically a singleton in the process it is loaded into.
+* ``.worker.(m)js`` - A file that is a web worker.
+
+  * Workers that use ctypes should use ``/* eslint-env mozilla/chrome-worker */``
+
+* Test files, see the section on :ref:`adding tests <adding-tests>`
+
+
 Understanding Rules and Errors
 ------------------------------
 
@@ -85,14 +103,6 @@ this is `difficult for ESLint to handle`_. Currently this may cause:
 * Extra definitions for globals in tests which means that the no undefined variables
   rule does not get triggered in some cases.
 
-I'm using an ES module
-^^^^^^^^^^^^^^^^^^^^^^
-
-* Use a ``.mjs`` extension for the file. ESLint will pick this up and automatically
-  treat it as a module.
-* If it is a system module (e.g. component definition or other non-frontend code),
-  use a ``.sys.mjs`` extension.
-
 This code should neither be linted nor formatted
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -124,11 +134,6 @@ I have valid code that is failing the ``no-undef`` rule or can't be parsed
 
   * ``/* eslint-env mozilla/frame-script */``
 
-* If you are writing a worker, then you may need to use the worker or chrome-worker environment:
-
-  * ``/* eslint-env worker */``
-  * ``/* eslint-env mozilla/chrome-worker */``
-
 * I use ``Services.scriptloader.loadSubScript``:
 
   * ``/* import-globals-from relative/path/to/file.js``

services/settings/RemoteSettings.worker.mjs

@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-/* eslint-env mozilla/chrome-worker */
-
 /**
  * A worker dedicated to Remote Settings.
  */

toolkit/components/promiseworker/worker/PromiseWorker.template.worker.js

@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-/* eslint-env commonjs, mozilla/chrome-worker */
+/* eslint-env commonjs */
 
 /**
  * A wrapper around `self` with extended capabilities designed

toolkit/components/telemetry/tests/unit/file_UninstallPing.worker.js

@@ -1,8 +1,6 @@
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/. */
 
-/* eslint-env mozilla/chrome-worker */
-
 /* import-globals-from /toolkit/components/workerloader/require.js */
 importScripts("resource://gre/modules/workers/require.js");
 

toolkit/mozapps/extensions/test/xpcshell/data/test_trash_directory.worker.js

@@ -1,8 +1,6 @@
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/. */
 
-/* eslint-env mozilla/chrome-worker */
-
 /* import-globals-from /toolkit/components/workerloader/require.js */
 importScripts("resource://gre/modules/workers/require.js");
 

tools/lint/eslint/eslint-plugin-mozilla/lib/configs/recommended.js

@@ -106,6 +106,13 @@ module.exports = {
         "mozilla/reject-importGlobalProperties": "off",
       },
     },
+    {
+      env: {
+        browser: false,
+        worker: true,
+      },
+      files: ["**/*.worker.js", "**/*.worker.mjs"],
+    },
   ],
 
   parserOptions: {