Add test for Realm's @@toStringTag

test/built-ins/Realm/prototype/Symbol.toStringTag.js

@@ -0,0 +1,22 @@
+// Copyright (C) 2021 Leo Balter. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-realm.prototype-@@tostringtag
+description: >
+  `Symbol.toStringTag` property descriptor
+info: |
+  The initial value of the @@toStringTag property is the String value
+  "Realm".
+
+  This property has the attributes { [[Writable]]: false, [[Enumerable]]:
+  false, [[Configurable]]: true }.
+includes: [propertyHelper.js]
+features: [callable-boundary-realms, Symbol.toStringTag]
+---*/
+
+verifyProperty(Realm.prototype, Symbol.toStringTag, {
+    value: 'Realm',
+    enumerable: false,
+    writable: false,
+    configurable: true
+});