1 files changed, 53 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/TypedArray/prototype/with/length-property-ignored.js b/js/src/tests/test262/built-ins/TypedArray/prototype/with/length-property-ignored.js
new file mode 100644
index 0000000000..a7217ba15b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/TypedArray/prototype/with/length-property-ignored.js
@@ -0,0 +1,53 @@
+// |reftest| shell-option(--enable-change-array-by-copy) skip-if(!Array.prototype.with||!xulRuntime.shell) -- change-array-by-copy is not enabled unconditionally, requires shell-options
+// Copyright (C) 2021 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-%typedarray%.prototype.with
+description: >
+  %TypedArray%.prototype.with reads the TypedArray length ignoring the .length property
+info: |
+  %TypedArray%.prototype.with ( index, value )
+
+  ...
+  3. Let len be O.[[ArrayLength]].
+  ...
+includes: [testTypedArray.js, compareArray.js]
+features: [TypedArray, change-array-by-copy]
+---*/
+
+testWithTypedArrayConstructors(TA => {
+  var ta = new TA([3, 1, 2]);
+  Object.defineProperty(ta, "length", { value: 2 })
+  var res = ta.with(0, 0);
+  assert.compareArray(res, [0, 1, 2]);
+  assert.sameValue(res.length, 3);
+
+  ta = new TA([3, 1, 2]);
+  Object.defineProperty(ta, "length", { value: 5 });
+  res = ta.with(0, 0);
+  assert.compareArray(res, [0, 1, 2]);
+  assert.sameValue(res.length, 3);
+});
+
+function setLength(length) {
+    Object.defineProperty(TypedArray.prototype, "length", {
+        get: () => length,
+    });
+}
+
+testWithTypedArrayConstructors(TA => {
+  var ta = new TA([3, 1, 2]);
+
+  setLength(2);
+  var res = ta.with(0, 0);
+  setLength(3);
+  assert.compareArray(res, [0, 1, 2]);
+
+  setLength(5);
+  res = ta.with(0, 0);
+  setLength(3);
+  assert.compareArray(res, [0, 1, 2]);
+});
+
+reportCompare(0, 0);