Testing the integrity level of non-extensible arrays.

graal-js/src/com.oracle.truffle.js.test/js/array_integrity_level.js

@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2025, 2025, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * Licensed under the Universal Permissive License v 1.0 as shown at http://oss.oracle.com/licenses/upl.
+ */
+
+load("assert.js");
+
+[[], new Array(100)].forEach(function (array) {
+    assertFalse(Object.isSealed(array));
+    assertFalse(Object.isFrozen(array));
+
+    Object.preventExtensions(array);
+
+    assertTrue(Object.isSealed(array));
+    assertFalse(Object.isFrozen(array)); // length is writable still
+
+    Object.defineProperty(array, 'length', { writable: false });
+
+    assertTrue(Object.isSealed(array));
+    assertTrue(Object.isFrozen(array));
+});
+
+var array = [,42];
+Object.preventExtensions(array); 
+assertFalse(Object.isSealed(array)); // has array[1]
+assertFalse(Object.isFrozen(array));
+delete array[1];
+assertTrue(Object.isSealed(array));
+assertFalse(Object.isFrozen(array)); // length is writable still
+Object.defineProperty(array, 'length', { length: 2, writable: false });
+assertTrue(Object.isSealed(array));
+assertTrue(Object.isFrozen(array));