diff -r 000000000000 -r 6474c204b198 toolkit/devtools/server/tests/unit/test_dbgsocket_connection_drop.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/devtools/server/tests/unit/test_dbgsocket_connection_drop.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,72 @@
+/**
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+/**
+ * Bug 755412 - checks if the server drops the connection on an improperly
+ * framed packet, i.e. when the length header is invalid.
+ */
+
+Cu.import("resource://gre/modules/devtools/dbg-server.jsm");
+Cu.import("resource://gre/modules/devtools/dbg-client.jsm");
+
+let port = 2929;
+
+function run_test()
+{
+  do_print("Starting test at " + new Date().toTimeString());
+  initTestDebuggerServer();
+
+  add_test(test_socket_conn_drops_after_invalid_header);
+  add_test(test_socket_conn_drops_after_invalid_header_2);
+  add_test(test_socket_conn_drops_after_too_long_header);
+  run_next_test();
+}
+
+function test_socket_conn_drops_after_invalid_header() {
+  return test_helper('fluff30:27:{"to":"root","type":"echo"}');
+}
+
+function test_socket_conn_drops_after_invalid_header_2() {
+  return test_helper('27asd:{"to":"root","type":"echo"}');
+}
+
+function test_socket_conn_drops_after_too_long_header() {
+  return test_helper('4305724038957487634549823475894325');
+}
+
+
+function test_helper(payload) {
+  try_open_listener();
+
+  let transport = debuggerSocketConnect("127.0.0.1", port);
+  transport.hooks = {
+    onPacket: function(aPacket) {
+      this.onPacket = function(aPacket) {
+        do_throw(new Error("This connection should be dropped."));
+        transport.close();
+      }
+
+      // Inject the payload directly into the stream.
+      transport._outgoing += payload;
+      transport._flushOutgoing();
+    },
+    onClosed: function(aStatus) {
+      do_check_true(true);
+      run_next_test();
+    },
+  };
+  transport.ready();
+}
+
+function try_open_listener()
+{
+  try {
+    do_check_true(DebuggerServer.openListener(port));
+  } catch (e) {
+    // In case the port is unavailable, pick a random one between 2000 and 65000.
+    port = Math.floor(Math.random() * (65000 - 2000 + 1)) + 2000;
+    try_open_listener();
+  }
+}