diff -r 000000000000 -r 6474c204b198 toolkit/components/search/tests/xpcshell/test_defaultEngine.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/components/search/tests/xpcshell/test_defaultEngine.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,99 @@
+/* Any copyright is dedicated to the Public Domain.
+ *    http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/*
+ * Test that currentEngine and defaultEngine properties can be set and yield the
+ * proper events and behavior (search results)
+ */
+
+"use strict";
+
+const Ci = Components.interfaces;
+
+Components.utils.import("resource://testing-common/httpd.js");
+
+let waitForEngines = {
+  "Test search engine": 1,
+  "A second test engine": 1
+};
+
+function search_observer(aSubject, aTopic, aData) {
+  let engine = aSubject.QueryInterface(Ci.nsISearchEngine);
+  do_print("Observer: " + aData + " for " + engine.name);
+
+  if (aData != "engine-added") {
+    return;
+  }
+
+  // If the engine is defined in `waitForEngines`, remove it from the list
+  if (waitForEngines[engine.name]) {
+    delete waitForEngines[engine.name];
+  } else {
+    // This engine is not one we're waiting for, so bail out early.
+    return;
+  }
+
+  // Only continue when both engines have been loaded.
+  if (Object.keys(waitForEngines).length)
+    return;
+
+  let search = Services.search;
+
+  let engine1 = search.getEngineByName("Test search engine");
+  let engine2 = search.getEngineByName("A second test engine");
+
+  search.defaultEngine = engine1;
+  do_check_eq(search.defaultEngine, engine1);
+  search.defaultEngine = engine2
+  do_check_eq(search.defaultEngine, engine2);
+  search.defaultEngine = engine1;
+  do_check_eq(search.defaultEngine, engine1);
+
+  // Test that hiding the currently-default engine affects the defaultEngine getter
+  // (when the default is hidden, we fall back to the first in the list, so move
+  // our second engine to that position)
+  search.moveEngine(engine2, 0);
+  engine1.hidden = true;
+  do_check_eq(search.defaultEngine, engine2);
+
+  // Test that the default engine is restored when it is unhidden
+  engine1.hidden = false;
+  do_check_eq(search.defaultEngine, engine1);
+
+  // Test that setting defaultEngine to an already-hidden engine works, but
+  // doesn't change the return value of the getter
+  engine2.hidden = true;
+  search.moveEngine(engine1, 0)
+  search.defaultEngine = engine2;
+  do_check_eq(search.defaultEngine, engine1);
+  engine2.hidden = false;
+  do_check_eq(search.defaultEngine, engine2);
+
+  do_test_finished();
+}
+
+function run_test() {
+  removeMetadata();
+  updateAppInfo();
+
+  let httpServer = new HttpServer();
+  httpServer.start(-1);
+  httpServer.registerDirectory("/", do_get_cwd());
+  let baseUrl = "http://localhost:" + httpServer.identity.primaryPort;
+
+  do_register_cleanup(function cleanup() {
+    httpServer.stop(function() {});
+    Services.obs.removeObserver(search_observer, "browser-search-engine-modified");
+  });
+
+  do_test_pending();
+
+  Services.obs.addObserver(search_observer, "browser-search-engine-modified", false);
+
+  Services.search.addEngine(baseUrl + "/data/engine.xml",
+                            Ci.nsISearchEngine.DATA_XML,
+                            null, false);
+  Services.search.addEngine(baseUrl + "/data/engine2.xml",
+                            Ci.nsISearchEngine.DATA_XML,
+                            null, false);
+}