1 files changed, 42 insertions, 0 deletions
diff --git a/docshell/test/mochitest/file_content_javascript_loads_root.html b/docshell/test/mochitest/file_content_javascript_loads_root.html
new file mode 100644
index 0000000000..b9f2c1faa7
--- /dev/null
+++ b/docshell/test/mochitest/file_content_javascript_loads_root.html
@@ -0,0 +1,42 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+<meta charset="utf-8">
+<script type="application/javascript">
+"use strict";
+
+window.onload = () => {
+  opener.postMessage("ready", "*");
+};
+
+// eslint-disable-next-line no-shadow
+function promiseMessage(source, filter = event => true) {
+  return new Promise(resolve => {
+    function listener(event) {
+      if (event.source == source && filter(event)) {
+        removeEventListener("message", listener);
+        resolve(event);
+      }
+    }
+    addEventListener("message", listener);
+  });
+}
+
+// Sends a message to the given target window and waits for the response.
+function ping(target) {
+  let msg = { ping: Math.random() };
+  target.postMessage(msg, "*");
+  return promiseMessage(
+    target,
+    event => event.data && event.data.pong == msg.ping
+  );
+}
+
+function setFrameLocation(name, uri) {
+  window[name].location = uri;
+}
+</script>
+</head>
+<body>
+</body>
+</html>