1 files changed, 45 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..7c2ffaf933
--- /dev/null
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/use-default-preference-values.js
@@ -0,0 +1,45 @@
+/**
+ * @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";
+
+// -----------------------------------------------------------------------------
+// Rule Definition
+// -----------------------------------------------------------------------------
+
+module.exports = function(context) {
+  // ---------------------------------------------------------------------------
+  // Public
+  //  --------------------------------------------------------------------------
+
+  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);
+    },
+  };
+};