--- a/accessible/tests/browser/.eslintrc.js
+++ b/accessible/tests/browser/.eslintrc.js
@@ -46,17 +46,16 @@ module.exports = { // eslint-disable-lin
     "waitForEvent": true,
     "waitForMultipleEvents": true,
     "invokeSetAttribute": true,
     "invokeSetStyle": true,
     "invokeFocus": true,
     "findAccessibleChildByID": true
   },
   "rules": {
-    "mozilla/mark-test-function-used": 1,
     "mozilla/no-aArgs": 1,
     "mozilla/no-cpows-in-tests": 1,
     "mozilla/reject-importGlobalProperties": 1,
     "mozilla/var-only-at-top-level": 1,
 
     "block-scoped-var": 2,
     "brace-style": [2, "1tbs"],
     "camelcase": 2,

--- a/browser/components/migration/tests/unit/test_fx_telemetry.js
+++ b/browser/components/migration/tests/unit/test_fx_telemetry.js
@@ -1,16 +1,15 @@
 /* Any copyright is dedicated to the Public Domain.
  * http://creativecommons.org/publicdomain/zero/1.0/ */
 
 /* globals do_get_tempdir */
 
 "use strict";
 
-/* exported run_test */
 function run_test() {
   run_next_test();
 }
 
 function readFile(file) {
   let stream = Cc["@mozilla.org/network/file-input-stream;1"]
                .createInstance(Ci.nsIFileInputStream);
   stream.init(file, -1, -1, Ci.nsIFileInputStream.CLOSE_ON_EOF);

--- a/browser/components/newtab/tests/xpcshell/test_NewTabPrefsProvider.js
+++ b/browser/components/newtab/tests/xpcshell/test_NewTabPrefsProvider.js
@@ -1,12 +1,11 @@
 "use strict";
 
 /* global XPCOMUtils, equal, Preferences, NewTabPrefsProvider, run_next_test */
-/* exported run_test */
 /* jscs:disable requireCamelCaseOrUpperCaseIdentifiers */
 
 const Cu = Components.utils;
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 Cu.import("resource://gre/modules/Preferences.jsm");
 
 XPCOMUtils.defineLazyModuleGetter(this, "NewTabPrefsProvider",
     "resource:///modules/NewTabPrefsProvider.jsm");

--- a/browser/components/newtab/tests/xpcshell/test_NewTabSearchProvider.js
+++ b/browser/components/newtab/tests/xpcshell/test_NewTabSearchProvider.js
@@ -1,12 +1,11 @@
 "use strict";
 
 /* global XPCOMUtils, NewTabSearchProvider, run_next_test, ok, equal, do_check_true, do_get_profile, Services */
-/* exported run_test */
 /* jscs:disable requireCamelCaseOrUpperCaseIdentifiers */
 
 const Cu = Components.utils;
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 Cu.import("resource://gre/modules/Services.jsm");
 
 XPCOMUtils.defineLazyModuleGetter(this, "NewTabSearchProvider",
     "resource:///modules/NewTabSearchProvider.jsm");
@@ -76,9 +75,8 @@ add_task(function* test_search() {
   let expectedEngineName = Services.search.currentEngine.name;
 
   // emitter should fire and return the new engine
   let [eventName, actualEngineName] = yield promise;
   equal(eventName, "browser-search-engine-modified", `emitter sent the correct event ${eventName}`);
   equal(expectedEngineName, actualEngineName, `emitter set the correct engine ${expectedEngineName}`);
   NewTabSearchProvider.search.uninit();
 });
-

--- a/browser/components/newtab/tests/xpcshell/test_PlacesProvider.js
+++ b/browser/components/newtab/tests/xpcshell/test_PlacesProvider.js
@@ -1,14 +1,13 @@
 "use strict";
 
 /* global XPCOMUtils, PlacesUtils, PlacesTestUtils, PlacesProvider, NetUtil */
 /* global do_get_profile, run_next_test, add_task */
 /* global equal, ok */
-/* exported run_test */
 
 const {
   utils: Cu,
   interfaces: Ci,
 } = Components;
 
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 

--- a/browser/experiments/test/xpcshell/.eslintrc.js
+++ b/browser/experiments/test/xpcshell/.eslintrc.js
@@ -3,13 +3,13 @@
 module.exports = {
   "extends": [
     "../../../../testing/xpcshell/xpcshell.eslintrc.js"
   ],
 
   "rules": {
     "no-unused-vars": ["error", {
       "vars": "all",
-      "varsIgnorePattern": "^(Cc|Ci|Cr|Cu|EXPORTED_SYMBOLS|run_test)$",
+      "varsIgnorePattern": "^(Cc|Ci|Cr|Cu|EXPORTED_SYMBOLS)$",
       "args": "none"
     }]
   }
 };

--- a/browser/extensions/formautofill/.eslintrc.js
+++ b/browser/extensions/formautofill/.eslintrc.js
@@ -8,17 +8,16 @@ module.exports = { // eslint-disable-lin
     "dump": true,
     "TextDecoder": false,
     "TextEncoder": false,
   },
 
   "rules": {
     // Rules from the mozilla plugin
     "mozilla/balanced-listeners": 2,
-    "mozilla/mark-test-function-used": 1,
     "mozilla/no-aArgs": 1,
     "mozilla/no-cpows-in-tests": 1,
     "mozilla/var-only-at-top-level": 1,
 
     "valid-jsdoc": [2, {
       "prefer": {
         "return": "returns",
       },

--- a/devtools/.eslintrc.js
+++ b/devtools/.eslintrc.js
@@ -32,17 +32,16 @@ module.exports = {
     "WebSocket": true,
     "XMLHttpRequest": true,
   },
   "rules": {
     // These are the rules that have been configured so far to match the
     // devtools coding style.
 
     // Rules from the mozilla plugin
-    "mozilla/mark-test-function-used": 1,
     "mozilla/no-aArgs": 1,
     "mozilla/no-cpows-in-tests": 2,
     "mozilla/no-single-arg-cu-import": 2,
     // See bug 1224289.
     "mozilla/reject-importGlobalProperties": 2,
     // devtools/shared/platform is special; see the README.md in that
     // directory for details.  We reject requires using explicit
     // subdirectories of this directory.

--- a/devtools/.eslintrc.xpcshell.js
+++ b/devtools/.eslintrc.xpcshell.js
@@ -8,14 +8,12 @@ module.exports = {
     "camelcase": 0,
     // Allow using undefined variables so that tests can refer to functions
     // and variables defined in head.js files, without having to maintain a
     // list of globals in each .eslintrc file.
     // Note that bug 1168340 will eventually help auto-registering globals
     // from head.js files.
     "no-undef": 0,
     "block-scoped-var": 0,
-    // Allow run_test to be unused in xpcshell
-    "no-unused-vars": [2, { "varsIgnorePattern": "run_test" }],
     // Tests can always import anything.
     "mozilla/reject-some-requires": 0,
   }
 };

--- a/testing/mochitest/browser.eslintrc.js
+++ b/testing/mochitest/browser.eslintrc.js
@@ -1,13 +1,14 @@
 // Parent config file for all browser-chrome files.
 module.exports = {
   "rules": {
-    "mozilla/import-headjs-globals": 2,
-    "mozilla/import-browserjs-globals": 2,
+    "mozilla/import-headjs-globals": 1,
+    "mozilla/import-browserjs-globals": 1,
+    "mozilla/mark-test-function-used": 1,
   },
 
   "env": {
     "browser": true,
     //"node": true
   },
 
   // All globals made available in the test environment.

--- a/testing/mochitest/chrome.eslintrc.js
+++ b/testing/mochitest/chrome.eslintrc.js
@@ -1,12 +1,13 @@
 // Parent config file for all mochitest files.
 module.exports = {
   rules: {
     "mozilla/import-headjs-globals": 1,
+    "mozilla/mark-test-function-used": 1,
   },
 
   "env": {
     "browser": true,
   },
 
   // All globals made available in the test environment.
   "globals": {

--- a/testing/mochitest/mochitest.eslintrc.js
+++ b/testing/mochitest/mochitest.eslintrc.js
@@ -1,12 +1,13 @@
 // Parent config file for all mochitest files.
 module.exports = {
   rules: {
     "mozilla/import-headjs-globals": 1,
+    "mozilla/mark-test-function-used": 1,
   },
 
   "env": {
     "browser": true,
   },
 
   // All globals made available in the test environment.
   "globals": {

--- a/testing/xpcshell/xpcshell.eslintrc.js
+++ b/testing/xpcshell/xpcshell.eslintrc.js
@@ -1,12 +1,13 @@
 // Parent config file for all xpcshell files.
 module.exports = {
   rules: {
     "mozilla/import-headjs-globals": 1,
+    "mozilla/mark-test-function-used": 1,
   },
 
   // All globals made available in the test environment.
   "globals": {
     "add_task": false,
     "add_test": false,
     "Assert": false,
     "deepEqual": false,

--- a/toolkit/components/extensions/.eslintrc.js
+++ b/toolkit/components/extensions/.eslintrc.js
@@ -27,17 +27,16 @@ module.exports = { // eslint-disable-lin
     "TabManager": true,
     "WindowListManager": true,
     "XPCOMUtils": true,
   },
 
   "rules": {
     // Rules from the mozilla plugin
     "mozilla/balanced-listeners": 2,
-    "mozilla/mark-test-function-used": 1,
     "mozilla/no-aArgs": 1,
     "mozilla/no-cpows-in-tests": 1,
     "mozilla/var-only-at-top-level": 1,
 
     "valid-jsdoc": [2, {
       "prefer": {
         "return": "returns",
       },

--- a/tools/lint/docs/linters/eslint-plugin-mozilla.rst
+++ b/tools/lint/docs/linters/eslint-plugin-mozilla.rst
@@ -67,18 +67,19 @@ The following patterns are supported:
 -  ``XPCOMUtils.defineLazyModuleGetter(this, "setNamedTimeout", ...)``
 -  ``loader.lazyGetter(this, "toolboxStrings"``
 -  ``XPCOMUtils.defineLazyGetter(this, "clipboardHelper"``
 
 
 mark-test-function-used
 -----------------------
 
-Simply marks test (the test method) as used. This avoids ESLint telling
-us that the function is never called.
+Simply marks `test` (the test method) or `run_test` as used when in mochitests
+or xpcshell tests respectively. This avoids ESLint telling us that the function
+is never called.
 
 
 no-aArgs
 --------
 
 Checks that function argument names don't start with lowercase 'a' followed by
 a capital letter. This is to prevent the use of Hungarian notation whereby the
 first letter is a prefix that indicates the type or intended use of a variable.

--- a/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/mark-test-function-used.js
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/mark-test-function-used.js
@@ -1,11 +1,12 @@
 /**
- * @fileoverview Simply marks test (the test method) as used. This avoids ESLint
- * telling us that the function is never called..
+ * @fileoverview Simply marks `test` (the test method) or `run_test` as used when
+ * in mochitests or xpcshell tests respectively. This avoids ESLint telling us
+ * that the function is never called.
  *
  * This Source Code Form is subject to the terms of the Mozilla Public
  * 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/.
  */
 
 "use strict";
 
@@ -17,16 +18,20 @@ var helpers = require("../helpers");
 
 module.exports = function(context) {
   // ---------------------------------------------------------------------------
   // Public
   // ---------------------------------------------------------------------------
 
   return {
     Program: function() {
-      if (!helpers.getIsBrowserMochitest(this)) {
+      if (helpers.getIsBrowserMochitest(this)) {
+        context.markVariableAsUsed("test");
         return;
       }
 
-      context.markVariableAsUsed("test");
+      if (helpers.getIsXpcshellTest(this)) {
+        context.markVariableAsUsed("run_test");
+        return;
+      }
     }
   };
 };