1 files changed, 35 insertions, 0 deletions
diff --git a/js/src/tests/test262/built-ins/Proxy/preventExtensions/trap-is-undefined-target-is-proxy.js b/js/src/tests/test262/built-ins/Proxy/preventExtensions/trap-is-undefined-target-is-proxy.js
new file mode 100644
index 0000000000..4eda6cef6b
--- /dev/null
+++ b/js/src/tests/test262/built-ins/Proxy/preventExtensions/trap-is-undefined-target-is-proxy.js
@@ -0,0 +1,35 @@
+// |reftest| module
+// Copyright (C) 2020 Alexey Shvayka. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-proxy-object-internal-methods-and-internal-slots-preventextensions
+description: >
+  If "preventExtensions" trap is null or undefined, [[PreventExtensions]] call
+  is properly forwarded to [[ProxyTarget]] (which is also a Proxy object).
+info: |
+  [[PreventExtensions]] ( )
+
+  [...]
+  4. Let target be O.[[ProxyTarget]].
+  5. Let trap be ? GetMethod(handler, "preventExtensions").
+  6. If trap is undefined, then
+    a. Return ? target.[[PreventExtensions]]().
+
+  [[PreventExtensions]] ( )
+
+  1. Return true.
+features: [Proxy, Reflect]
+flags: [module]
+---*/
+
+import * as ns from "./trap-is-undefined-target-is-proxy.js";
+
+var nsTarget = new Proxy(ns, {});
+var nsProxy = new Proxy(nsTarget, {
+  preventExtensions: undefined,
+});
+
+assert(Reflect.preventExtensions(nsProxy));
+
+reportCompare(0, 0);