diff -r 000000000000 -r 6474c204b198 toolkit/mozapps/extensions/test/xpcshell/test_bug521905.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/mozapps/extensions/test/xpcshell/test_bug521905.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,59 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+const ADDON = "test_bug521905";
+const ID = "bug521905@tests.mozilla.org";
+
+// Disables security checking our updates which haven't been signed
+Services.prefs.setBoolPref("extensions.checkUpdateSecurity", false);
+
+function run_test() {
+  // This test is only relevant on builds where the version is included in the
+  // checkCompatibility preference name
+  if (isNightlyChannel()) {
+    return;
+  }
+
+  do_test_pending();
+  createAppInfo("xpcshell@tests.mozilla.org", "XPCShell", "2.0pre", "2");
+
+  startupManager();
+  AddonManager.checkCompatibility = false;
+
+  installAllFiles([do_get_addon(ADDON)], function() {
+    restartManager();
+
+    AddonManager.getAddonByID(ID, function(addon) {
+      do_check_neq(addon, null);
+      do_check_true(addon.isActive);
+
+      do_execute_soon(run_test_1);
+    });
+  });
+}
+
+function run_test_1() {
+  Services.prefs.setBoolPref("extensions.checkCompatibility.2.0pre", true);
+
+  restartManager();
+  AddonManager.getAddonByID(ID, function(addon) {
+    do_check_neq(addon, null);
+    do_check_false(addon.isActive);
+
+    do_execute_soon(run_test_2);
+  });
+}
+
+function run_test_2() {
+  Services.prefs.setBoolPref("extensions.checkCompatibility.2.0p", false);
+
+  restartManager();
+  AddonManager.getAddonByID(ID, function(addon) {
+    do_check_neq(addon, null);
+    do_check_false(addon.isActive);
+
+    do_execute_soon(do_test_finished);
+  });
+}