diff -r 000000000000 -r 6474c204b198 toolkit/devtools/server/tests/unit/test_nesting-03.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/devtools/server/tests/unit/test_nesting-03.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,51 @@
+/* -*- Mode: javascript; js-indent-level: 2; -*- */
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test that we can detect nested event loops in tabs with the same URL.
+
+var gClient1, gClient2, gThreadClient1, gThreadClient2;
+
+function run_test() {
+  initTestDebuggerServer();
+  addTestGlobal("test-nesting1");
+  addTestGlobal("test-nesting1");
+  // Conect the first client to the first debuggee.
+  gClient1 = new DebuggerClient(DebuggerServer.connectPipe());
+  gClient1.connect(function () {
+    attachTestThread(gClient1, "test-nesting1", function (aResponse, aTabClient, aThreadClient) {
+      gThreadClient1 = aThreadClient;
+      start_second_connection();
+    });
+  });
+  do_test_pending();
+}
+
+function start_second_connection() {
+  gClient2 = new DebuggerClient(DebuggerServer.connectPipe());
+  gClient2.connect(function () {
+    attachTestThread(gClient2, "test-nesting1", function (aResponse, aTabClient, aThreadClient) {
+      gThreadClient2 = aThreadClient;
+      test_nesting();
+    });
+  });
+}
+
+function test_nesting() {
+  const { resolve, reject, promise: p } = promise.defer();
+
+  gThreadClient1.resume(aResponse => {
+    do_check_eq(aResponse.error, "wrongOrder");
+    gThreadClient2.resume(aResponse => {
+      do_check_true(!aResponse.error);
+      do_check_eq(aResponse.from, gThreadClient2.actor);
+
+      gThreadClient1.resume(aResponse => {
+        do_check_true(!aResponse.error);
+        do_check_eq(aResponse.from, gThreadClient1.actor);
+
+        gClient1.close(() => finishClient(gClient2));
+      });
+    });
+  });
+}