diff -r 000000000000 -r 6474c204b198 toolkit/devtools/server/tests/unit/test_longstringgrips-02.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/devtools/server/tests/unit/test_longstringgrips-02.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,60 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+var gDebuggee;
+var gClient;
+var gThreadClient;
+
+function run_test()
+{
+  initTestDebuggerServer();
+  gDebuggee = addTestGlobal("test-grips");
+  gDebuggee.eval(function stopMe(arg1) {
+    debugger;
+  }.toString());
+
+  gClient = new DebuggerClient(DebuggerServer.connectPipe());
+  gClient.connect(function() {
+    attachTestTabAndResume(
+      gClient, "test-grips", function(aResponse, aTabClient, aThreadClient) {
+        gThreadClient = aThreadClient;
+        test_longstring_grip();
+      });
+  });
+  do_test_pending();
+}
+
+function test_longstring_grip()
+{
+  DebuggerServer.LONG_STRING_LENGTH = 200;
+
+  gThreadClient.addOneTimeListener("paused", function(aEvent, aPacket) {
+    try {
+      let fakeLongStringGrip = {
+        type: "longString",
+        length: 1000000,
+        actor: "123fakeActor123",
+        initial: ""
+      };
+      let longStringClient = gThreadClient.pauseLongString(fakeLongStringGrip);
+      longStringClient.substring(22, 28, function (aResponse) {
+        try {
+          do_check_true(!!aResponse.error,
+                        "We should not get a response, but an error.");
+        } finally {
+          gThreadClient.resume(function() {
+            finishClient(gClient);
+          });
+        }
+      });
+    } catch(error) {
+      gThreadClient.resume(function() {
+        finishClient(gClient);
+        do_throw(error);
+      });
+    }
+  });
+
+  gDebuggee.eval('stopMe()');
+}
+