1 files changed, 28 insertions, 0 deletions
diff --git a/testing/web-platform/tests/webmessaging/Channel_postMessage_ports_readonly_array.any.js b/testing/web-platform/tests/webmessaging/Channel_postMessage_ports_readonly_array.any.js
new file mode 100644
index 0000000000..032a54e710
--- /dev/null
+++ b/testing/web-platform/tests/webmessaging/Channel_postMessage_ports_readonly_array.any.js
@@ -0,0 +1,28 @@
+// META: title=postMessage(): read-only ports array
+
+    "use strict";
+
+    var TargetPort = null;
+    var description = "The postMessage() method - Make new ports into a read only array.";
+
+    var t = async_test("Test Description: " + description);
+
+    var channel = new MessageChannel();
+
+    TargetPort = channel.port2;
+    TargetPort.start();
+    TargetPort.addEventListener("message", t.step_func(TestMessageEvent), true);
+
+    var channel2 = new MessageChannel();
+
+    channel.port1.postMessage("ports", [channel2.port1]);
+
+    function TestMessageEvent(evt)
+    {
+        var channel3 = new MessageChannel();
+        assert_throws_js(TypeError, () => {
+            evt.ports.push(channel3.port1);
+        }, "ports is a frozen object");
+        assert_equals(evt.ports.length, 1, "ports is a read only array with length == 1.");
+        t.done();
+    }