From 96ba20f096d61bccc20cddbcbbba1806c82c0723 Mon Sep 17 00:00:00 2001
From: Lyle Underwood <lyleunderwood@gmail.com>
Date: Thu, 18 Jul 2019 19:35:55 +0200
Subject: [PATCH] fix: ignore arrow functions with predicates in arrow-parens

---
 src/rules/arrowParens.js              | 6 ++++++
 tests/rules/assertions/arrowParens.js | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/src/rules/arrowParens.js b/src/rules/arrowParens.js
index b7ad295b..449b00a0 100644
--- a/src/rules/arrowParens.js
+++ b/src/rules/arrowParens.js
@@ -50,6 +50,12 @@ export default {
         return;
       }
 
+      // Similarly, a predicate always requires parens just like a return type
+      // does, and therefore this case can also be safely ignored.
+      if (node.predicate) {
+        return;
+      }
+
       // "as-needed", { "requireForBlockBody": true }: x => x
       if (
         requireForBlockBody &&
diff --git a/tests/rules/assertions/arrowParens.js b/tests/rules/assertions/arrowParens.js
index 435778fb..338c4644 100644
--- a/tests/rules/assertions/arrowParens.js
+++ b/tests/rules/assertions/arrowParens.js
@@ -331,6 +331,8 @@ export default {
     {code: '<T>(a: T) => { return a; }',
       options: ['always', {requireForBlockBody: true}]},
     {code: '<T>(a: T) => { return a; }',
+      options: ['as-needed', {requireForBlockBody: true}]},
+    {code: '(a): %checks => typeof a === "number"',
       options: ['as-needed', {requireForBlockBody: true}]}
 
   ]