diff -r 000000000000 -r 6474c204b198 testing/mochitest/dynamic/getMyDirectory.sjs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/testing/mochitest/dynamic/getMyDirectory.sjs	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,15 @@
+function handleRequest(request, response)
+{
+  var file;
+  getObjectState("SERVER_ROOT", function(serverRoot)
+  {
+    var ref = request.getHeader("Referer").split("?")[0];
+    // 8 is "https://".length which is the longest string before the host.
+    var pathStart = ref.indexOf("/", 8) + 1;
+    var pathEnd = ref.lastIndexOf("/") + 1;
+    file = serverRoot.getFile(ref.substring(pathStart, pathEnd) + "x");
+  });
+
+  response.setHeader("Content-Type", "text/plain", false);
+  response.write(file.path.substr(0, file.path.length-1));
+}