1 files changed, 50 insertions, 0 deletions
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/use-default-preference-values.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/use-default-preference-values.js
new file mode 100644
index 0000000000..3c621bed1b
--- /dev/null
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/use-default-preference-values.js
@@ -0,0 +1,50 @@
+/**
+ * @fileoverview Require providing a second parameter to get*Pref
+ * methods instead of using a try/catch block.
+ *
+ * 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";
+
+module.exports = {
+  meta: {
+    docs: {
+      url:
+        "https://firefox-source-docs.mozilla.org/code-quality/lint/linters/eslint-plugin-mozilla/use-default-preference-values.html",
+    },
+    type: "suggestion",
+  },
+
+  create(context) {
+    return {
+      TryStatement(node) {
+        let types = ["Bool", "Char", "Float", "Int"];
+        let methods = types.map(type => "get" + type + "Pref");
+        if (
+          node.block.type != "BlockStatement" ||
+          node.block.body.length != 1
+        ) {
+          return;
+        }
+
+        let firstStm = node.block.body[0];
+        if (
+          firstStm.type != "ExpressionStatement" ||
+          firstStm.expression.type != "AssignmentExpression" ||
+          firstStm.expression.right.type != "CallExpression" ||
+          firstStm.expression.right.callee.type != "MemberExpression" ||
+          firstStm.expression.right.callee.property.type != "Identifier" ||
+          !methods.includes(firstStm.expression.right.callee.property.name)
+        ) {
+          return;
+        }
+
+        let msg = "provide a default value instead of using a try/catch block";
+        context.report(node, msg);
+      },
+    };
+  },
+};