1 files changed, 37 insertions, 0 deletions
diff --git a/dom/tests/mochitest/whatwg/postMessage_override_helper.html b/dom/tests/mochitest/whatwg/postMessage_override_helper.html
new file mode 100644
index 0000000000..901e3af7bb
--- /dev/null
+++ b/dom/tests/mochitest/whatwg/postMessage_override_helper.html
@@ -0,0 +1,37 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <title>Overriding postMessage and dispatchEvent bindings</title>
+  <script type="application/javascript">
+    window.postMessage = function (evt) {
+      window.parent.postMessage("FAIL overridden postMessage called", "*");
+    };
+
+    var count = 0;
+
+    function receiveMessage(evt) {
+      count++;
+      if (count == 2) {
+        window.dispatchEvent = function(evt) {
+          window.parent.postMessage("FAIL", "*");
+          throw "dispatchEvent threw";
+        };
+      }
+
+      window.parent.postMessage(evt.data, "http://mochi.test:8888");
+    }
+
+    function setup() {
+      var target = document.getElementById("location");
+      target.textContent = location.hostname + ":" + (location.port || 80);
+    }
+
+    window.addEventListener("message", receiveMessage);
+
+    window.addEventListener("load", setup);
+  </script>
+</head>
+<body>
+<h1 id="location">No location!</h1>
+</body>
+</html>