1 files changed, 45 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/Array/prototype/at/returns-undefined-for-holes-in-sparse-arrays.js b/js/src/tests/test262/built-ins/Array/prototype/at/returns-undefined-for-holes-in-sparse-arrays.js
new file mode 100644
index 0000000000..4c9a573b53
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Array/prototype/at/returns-undefined-for-holes-in-sparse-arrays.js
@@ -0,0 +1,45 @@
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-array.prototype.at
+description: >
+  Returns the item value at the specified index, respecting holes in sparse arrays.
+info: |
+  Array.prototype.at ( )
+
+  Let O be ? ToObject(this value).
+  Let len be ? LengthOfArrayLike(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: [Array.prototype.at]
+---*/
+assert.sameValue(
+  typeof Array.prototype.at,
+  'function',
+  'The value of `typeof Array.prototype.at` is expected to be "function"'
+);
+
+let a = [0, 1, , 3, 4, , 6];
+
+assert.sameValue(a.at(0), 0, 'a.at(0) must return 0');
+assert.sameValue(a.at(1), 1, 'a.at(1) must return 1');
+assert.sameValue(a.at(2), undefined, 'a.at(2) returns undefined');
+assert.sameValue(a.at(3), 3, 'a.at(3) must return 3');
+assert.sameValue(a.at(4), 4, 'a.at(4) must return 4');
+assert.sameValue(a.at(5), undefined, 'a.at(5) returns undefined');
+assert.sameValue(a.at(6), 6, 'a.at(6) must return 6');
+assert.sameValue(a.at(-0), 0, 'a.at(-0) must return 0');
+assert.sameValue(a.at(-1), 6, 'a.at(-1) must return 6');
+assert.sameValue(a.at(-2), undefined, 'a.at(-2) returns undefined');
+assert.sameValue(a.at(-3), 4, 'a.at(-3) must return 4');
+assert.sameValue(a.at(-4), 3, 'a.at(-4) must return 3');
+assert.sameValue(a.at(-5), undefined, 'a.at(-5) returns undefined');
+assert.sameValue(a.at(-6), 1, 'a.at(-6) must return 1');
+
+reportCompare(0, 0);