From 14aa2d8b75fd16378c2be183fd5b008712547ed4 Mon Sep 17 00:00:00 2001
From: Jordan Harband <ljharb@gmail.com>
Date: Fri, 17 Mar 2023 11:32:43 -0700
Subject: [PATCH] [Fix] `filter`: properly increment the counter

---
 Iterator.prototype.filter/implementation.js |  2 +-
 test/Iterator.prototype.filter.js           | 44 +++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/Iterator.prototype.filter/implementation.js b/Iterator.prototype.filter/implementation.js
index d5ce5fe..31ce962 100644
--- a/Iterator.prototype.filter/implementation.js
+++ b/Iterator.prototype.filter/implementation.js
@@ -26,8 +26,8 @@ module.exports = function filter(predicate) {
 	}
 
 	var sentinel = {};
+	var counter = 0; // step 3.a
 	var closure = function () {
-		var counter = 0; // step 3.a
 		// eslint-disable-next-line no-constant-condition
 		while (true) { // step 3.b
 			var next = IteratorStep(iterated); // step 3.b.i
diff --git a/test/Iterator.prototype.filter.js b/test/Iterator.prototype.filter.js
index 1efcc80..444e096 100644
--- a/test/Iterator.prototype.filter.js
+++ b/test/Iterator.prototype.filter.js
@@ -55,6 +55,50 @@ module.exports = {
 
 			st.end();
 		});
+
+		t.test('262: test/built-ins/Iterator/prototype/filter/predicate-args', function (st) {
+			var g = function g() {
+				var arr = ['a', 'b', 'c'];
+				var i = 0;
+				return {
+					next: function () {
+						try {
+							return {
+								value: arr[i],
+								done: i >= arr.length
+							};
+						} finally {
+							i += 1;
+						}
+					}
+				};
+			};
+			var assertionCount = 0;
+			var iter = filter(
+				g(),
+				function (value, count) {
+					if (value === 'a') {
+						st.equal(count, 0, 'first iteration');
+					} else if (value === 'b') {
+						st.equal(count, 1, 'second iteration');
+					} else if (value === 'c') {
+						st.equal(count, 2, 'third iteration');
+					} else {
+						st.fail('unexpected iteration');
+					}
+					assertionCount += 1;
+					return true;
+				}
+			);
+
+			st.equal(assertionCount, 0, 'prior to iteration');
+
+			testIterator(iter, ['a', 'b', 'c'], st, 'iteration');
+
+			st.equal(assertionCount, 3);
+
+			st.end();
+		});
 	},
 	index: function () {
 		test('Iterator.prototype.' + fnName + ': index', function (t) {