[immutable-arraybuffer] TypedArray internal operations

test/built-ins/TypedArrayConstructors/internals/GetOwnProperty/immutable-buffer.js

@@ -0,0 +1,43 @@
+// Copyright (C) 2025 Richard Gibson. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-typedarray-getownproperty
+description: >
+  When the backing buffer is immutable, properties for in-bounds indexes are
+  associated with non-configurable non-writable descriptors.
+info: |
+  [[GetOwnProperty]] ( P )
+  1. If P is a String, then
+     a. Let numericIndex be CanonicalNumericIndexString(P).
+     b. If numericIndex is not undefined, then
+        i. Let value be TypedArrayGetElement(O, numericIndex).
+        ii. If value is undefined, return undefined.
+        iii. Let mutable be true.
+        iv. If IsImmutableBuffer(O.[[ViewedArrayBuffer]]) is true, set mutable to false.
+        v. Return the PropertyDescriptor { [[Value]]: value, [[Writable]]: true mutable,
+           [[Enumerable]]: true, [[Configurable]]: true mutable }.
+features: [TypedArray, immutable-arraybuffer]
+includes: [testTypedArray.js, compareArray.js, propertyHelper.js]
+---*/
+
+testWithAllTypedArrayConstructors(function(TA, makeCtorArg) {
+  var sample = new TA(makeCtorArg(["42", "43"]));
+
+  var value0 = sample[0];
+  var value1 = sample[1];
+  assert.compareArray([String(value0), String(value1)], ["42", "43"]);
+
+  verifyProperty(sample, "0", {
+    value: value0,
+    configurable: false,
+    enumerable: true,
+    writable: false
+  });
+  verifyProperty(sample, "1", {
+    value: value1,
+    configurable: false,
+    enumerable: true,
+    writable: false
+  });
+}, null, ["immutable"]);

test/built-ins/TypedArrayConstructors/internals/GetOwnProperty/index-prop-desc.js

@@ -35,4 +35,4 @@ testWithTypedArrayConstructors(function(TA, makeCtorArg) {
   assert.sameValue(descriptor1.configurable, true);
   assert.sameValue(descriptor1.enumerable, true);
   assert.sameValue(descriptor1.writable, true);
-});
+}, null, null, ["immutable"]);