Bug 1231963 - handle top-level "this.mumble" assignments in eslint; r=mikeratcliffe

.eslintrc

@@ -6,6 +6,7 @@
   "rules": {
     "mozilla/components-imports": 1,
     "mozilla/import-globals-from": 1,
+    "mozilla/this-top-level-scope": 1,
   },
   "env": {
     "es6": true

testing/eslint-plugin-mozilla/lib/index.js

@@ -25,6 +25,7 @@ module.exports = {
     "mark-test-function-used": require("../lib/rules/mark-test-function-used"),
     "no-aArgs": require("../lib/rules/no-aArgs"),
     "no-cpows-in-tests": require("../lib/rules/no-cpows-in-tests"),
+    "this-top-level-scope": require("../lib/rules/this-top-level-scope.js"),
     "var-only-at-top-level": require("../lib/rules/var-only-at-top-level")
   },
   rulesConfig: {
@@ -36,6 +37,7 @@ module.exports = {
     "mark-test-function-used": 0,
     "no-aArgs": 0,
     "no-cpows-in-tests": 0,
+    "this-top-level-scope": 0,
     "var-only-at-top-level": 0
   }
 };

testing/eslint-plugin-mozilla/lib/rules/this-top-level-scope.js

@@ -0,0 +1,33 @@
+/**
+ * @fileoverview Marks "this.var = x" as top-level definition of "var".
+ *
+ * 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";
+
+// -----------------------------------------------------------------------------
+// Rule Definition
+// -----------------------------------------------------------------------------
+
+var helpers = require("../helpers");
+
+module.exports = function(context) {
+
+  // ---------------------------------------------------------------------------
+  // Public
+  //  --------------------------------------------------------------------------
+
+  return {
+    "AssignmentExpression": function(node) {
+      if (helpers.getIsGlobalScope(context) &&
+          node.left.type === "MemberExpression" &&
+          node.left.object.type === "ThisExpression" &&
+          node.left.property.type === "Identifier") {
+        helpers.addGlobals([node.left.property.name], context);
+      }
+    }
+  };
+};