From 23746f8babace7c2354368d6fb0881be26e19c41 Mon Sep 17 00:00:00 2001
From: comrem <53528033+comrem@users.noreply.github.com>
Date: Wed, 27 Apr 2022 17:02:25 +0200
Subject: [PATCH] fix(eslint-plugin): [comma-spacing] verify `nextToken` exists
 (#4868)

* eslint-plugin/rules/comma-spacing: add check to verify nextToken exists

* fix(eslint-plugin): run prettier and use builtin functions

* fix(eslint-plugin): [comma-spacing] add unit test
---
 packages/eslint-plugin/src/rules/comma-spacing.ts   |  2 +-
 .../eslint-plugin/tests/rules/comma-spacing.test.ts | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/packages/eslint-plugin/src/rules/comma-spacing.ts b/packages/eslint-plugin/src/rules/comma-spacing.ts
index 2774324d259..336017db1b3 100644
--- a/packages/eslint-plugin/src/rules/comma-spacing.ts
+++ b/packages/eslint-plugin/src/rules/comma-spacing.ts
@@ -177,7 +177,7 @@ export default createRule<Options, MessageIds>({
             isCommaToken(prevToken) || ignoredTokens.has(token)
               ? null
               : prevToken,
-            isCommaToken(nextToken) || ignoredTokens.has(token)
+            (nextToken && isCommaToken(nextToken)) || ignoredTokens.has(token)
               ? null
               : nextToken,
           );
diff --git a/packages/eslint-plugin/tests/rules/comma-spacing.test.ts b/packages/eslint-plugin/tests/rules/comma-spacing.test.ts
index 9ab7def96d9..37eb6e2e3ad 100644
--- a/packages/eslint-plugin/tests/rules/comma-spacing.test.ts
+++ b/packages/eslint-plugin/tests/rules/comma-spacing.test.ts
@@ -281,6 +281,7 @@ ruleTester.run('comma-spacing', rule, {
     'class Foo<T, T1> {}',
     'interface Foo<T, T1,>{}',
     'interface A<> {}',
+    'let foo,',
   ],
 
   invalid: [
@@ -787,5 +788,17 @@ ruleTester.run('comma-spacing', rule, {
         },
       ],
     },
+    {
+      code: 'let foo ,',
+      output: 'let foo,',
+      errors: [
+        {
+          messageId: 'unexpected',
+          column: 9,
+          line: 1,
+          data: { loc: 'before' },
+        },
+      ],
+    },
   ],
 });