Bug 1779988 - Part 2: Add ESLint rule that rejects multiple `ChromeUtils.defineESModuleGetters` call on the same object. r=Standard8

Differential Revision: https://phabricator.services.mozilla.com/D152880

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

@@ -55,6 +55,7 @@ The plugin implements the following rules:
    eslint-plugin-mozilla/reject-importGlobalProperties
    eslint-plugin-mozilla/reject-lazy-imports-into-globals
    eslint-plugin-mozilla/reject-mixing-eager-and-lazy
+   eslint-plugin-mozilla/reject-multiple-getters-calls
    eslint-plugin-mozilla/reject-osfile
    eslint-plugin-mozilla/reject-relative-requires
    eslint-plugin-mozilla/reject-requires-await

docs/code-quality/lint/linters/eslint-plugin-mozilla/reject-multiple-getters-calls.rst

@@ -0,0 +1,27 @@
+reject-multiple-getters-calls
+=============================
+
+Rejects multiple calls on ``ChromeUtils.defineESModuleGetters`` for the same
+target in the same context.
+
+Examples of incorrect code for this rule:
+-----------------------------------------
+
+.. code-block:: js
+
+    ChromeUtils.defineESModuleGetters(lazy, {
+      AppConstants: "resource://gre/modules/AppConstants.sys.mjs",
+    });
+    ChromeUtils.defineESModuleGetters(lazy, {
+      PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
+    });
+
+Examples of correct code for this rule:
+---------------------------------------
+
+.. code-block:: js
+
+    ChromeUtils.defineESModuleGetters(lazy, {
+      AppConstants: "resource://gre/modules/AppConstants.sys.mjs",
+      PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
+    });

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

@@ -165,6 +165,7 @@ module.exports = {
     "mozilla/reject-addtask-only": "error",
     "mozilla/reject-chromeutils-import-params": "error",
     "mozilla/reject-importGlobalProperties": ["error", "allownonwebidl"],
+    "mozilla/reject-multiple-getters-calls": "error",
     "mozilla/reject-osfile": "warn",
     "mozilla/reject-scriptableunicodeconverter": "warn",
     "mozilla/rejects-requires-await": "error",

tools/lint/eslint/eslint-plugin-mozilla/lib/index.js

@@ -66,6 +66,7 @@ module.exports = {
     "reject-importGlobalProperties": require("../lib/rules/reject-importGlobalProperties"),
     "reject-lazy-imports-into-globals": require("../lib/rules/reject-lazy-imports-into-globals"),
     "reject-mixing-eager-and-lazy": require("../lib/rules/reject-mixing-eager-and-lazy"),
+    "reject-multiple-getters-calls": require("../lib/rules/reject-multiple-getters-calls"),
     "reject-osfile": require("../lib/rules/reject-osfile"),
     "reject-scriptableunicodeconverter": require("../lib/rules/reject-scriptableunicodeconverter"),
     "reject-relative-requires": require("../lib/rules/reject-relative-requires"),

tools/lint/eslint/eslint-plugin-mozilla/lib/rules/reject-multiple-getters-calls.js

@@ -0,0 +1,81 @@
+/**
+ * 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";
+
+const helpers = require("../helpers");
+
+function findStatement(node) {
+  while (node && node.type !== "ExpressionStatement") {
+    node = node.parent;
+  }
+
+  return node;
+}
+
+function isIdentifier(node, id) {
+  return node && node.type === "Identifier" && node.name === id;
+}
+
+module.exports = {
+  meta: {
+    docs: {
+      url:
+        "https://firefox-source-docs.mozilla.org/code-quality/lint/linters/eslint-plugin-mozilla/reject-multiple-getters-calls.html",
+    },
+    messages: {
+      rejectMultipleCalls:
+        "ChromeUtils.defineESModuleGetters is already called for {{target}} in the same context. Please merge those calls",
+    },
+    type: "suggestion",
+  },
+
+  create(context) {
+    const parentToTargets = new Map();
+
+    return {
+      CallExpression(node) {
+        let callee = node.callee;
+        if (
+          callee.type === "MemberExpression" &&
+          isIdentifier(callee.object, "ChromeUtils") &&
+          isIdentifier(callee.property, "defineESModuleGetters")
+        ) {
+          const stmt = findStatement(node);
+          if (!stmt) {
+            return;
+          }
+
+          let target;
+          try {
+            target = helpers.getASTSource(node.arguments[0]);
+          } catch (e) {
+            return;
+          }
+
+          const parent = stmt.parent;
+          let targets;
+          if (parentToTargets.has(parent)) {
+            targets = parentToTargets.get(parent);
+          } else {
+            targets = new Set();
+            parentToTargets.set(parent, targets);
+          }
+
+          if (targets.has(target)) {
+            context.report({
+              node,
+              messageId: "rejectMultipleCalls",
+              data: { target },
+            });
+          }
+
+          targets.add(target);
+        }
+      },
+    };
+  },
+};

tools/lint/eslint/eslint-plugin-mozilla/tests/reject-multiple-getters-calls.js

@@ -0,0 +1,60 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// ------------------------------------------------------------------------------
+// Requirements
+// ------------------------------------------------------------------------------
+
+var rule = require("../lib/rules/reject-multiple-getters-calls");
+var RuleTester = require("eslint").RuleTester;
+
+const ruleTester = new RuleTester();
+
+// ------------------------------------------------------------------------------
+// Tests
+// ------------------------------------------------------------------------------
+
+function invalidCode(code) {
+  return { code, errors: [{ messageId: "rejectMultipleCalls" }] };
+}
+
+ruleTester.run("reject-multiple-getters-calls", rule, {
+  valid: [
+    `
+      ChromeUtils.defineESModuleGetters(lazy, {
+        AppConstants: "resource://gre/modules/AppConstants.sys.mjs",
+        PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
+      });
+    `,
+    `
+      ChromeUtils.defineESModuleGetters(lazy, {
+        AppConstants: "resource://gre/modules/AppConstants.sys.mjs",
+      });
+      ChromeUtils.defineESModuleGetters(window, {
+        PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
+      });
+    `,
+    `
+      ChromeUtils.defineESModuleGetters(lazy, {
+        AppConstants: "resource://gre/modules/AppConstants.sys.mjs",
+      });
+      if (cond) {
+        ChromeUtils.defineESModuleGetters(lazy, {
+          PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
+        });
+      }
+    `,
+  ],
+  invalid: [
+    invalidCode(`
+      ChromeUtils.defineESModuleGetters(lazy, {
+        AppConstants: "resource://gre/modules/AppConstants.sys.mjs",
+      });
+      ChromeUtils.defineESModuleGetters(lazy, {
+        PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
+      });
+    `),
+  ],
+});