1 files changed, 31 insertions, 0 deletions
diff --git a/js/src/tests/ecma_2017/AsyncFunctions/subclass.js b/js/src/tests/ecma_2017/AsyncFunctions/subclass.js
new file mode 100644
index 000000000..da20ab19b
--- /dev/null
+++ b/js/src/tests/ecma_2017/AsyncFunctions/subclass.js
@@ -0,0 +1,31 @@
+// |reftest| skip-if(!xulRuntime.shell) -- needs drainJobQueue
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+const AsyncFunction = async function(){}.constructor;
+
+class MyAsync extends AsyncFunction {}
+
+// MyGen inherits from %AsyncFunction%.
+assertEq(Object.getPrototypeOf(MyAsync), AsyncFunction);
+
+// MyGen.prototype inherits from %AsyncFunctionPrototype%.
+assertEq(Object.getPrototypeOf(MyAsync.prototype), AsyncFunction.prototype);
+
+var fn = new MyAsync("return await 'ok';");
+
+// fn inherits from MyAsync.prototype.
+assertEq(Object.getPrototypeOf(fn), MyAsync.prototype);
+
+// Ensure the new async function can be executed.
+var promise = fn();
+
+// promise inherits from %Promise.prototype%.
+assertEq(Object.getPrototypeOf(promise), Promise.prototype);
+
+// Computes the expected result.
+assertEventuallyEq(promise, "ok");
+
+if (typeof reportCompare === "function")
+    reportCompare(0, 0);