1 files changed, 32 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/String/prototype/at/returns-code-unit.js b/js/src/tests/test262/built-ins/String/prototype/at/returns-code-unit.js
new file mode 100644
index 0000000000..08b1e049e2
--- /dev/null
+++ b/js/src/tests/test262/built-ins/String/prototype/at/returns-code-unit.js
@@ -0,0 +1,32 @@
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-String.prototype.at
+description: >
+  The method should return an Iterator instance.
+info: |
+  String.prototype.at ( )
+
+  Let O be ? ToObject(this value).
+  Let len be ? LengthOfStringLike(O).
+  Let relativeIndex be ? ToInteger(index).
+  If relativeIndex ≥ 0, then
+    Let k be relativeIndex.
+  Else,
+    Let k be len + relativeIndex.
+  If k < 0 or k ≥ len, then return undefined.
+  Return ? Get(O, ! ToString(k)).
+
+features: [String.prototype.at]
+---*/
+assert.sameValue(typeof String.prototype.at, 'function');
+
+let s = "12\uD80034";
+
+assert.sameValue(s.at(0), "1", 's.at(0) must return "1"');
+assert.sameValue(s.at(1), "2", 's.at(1) must return "2"');
+assert.sameValue(s.at(2), "\uD800", 's.at(2) must return "\\uD800"');
+assert.sameValue(s.at(3), "3", 's.at(3) must return "3"');
+assert.sameValue(s.at(4), "4", 's.at(4) must return "4"');
+
+reportCompare(0, 0);