diff -r 000000000000 -r 6474c204b198 toolkit/components/search/tests/xpcshell/test_identifiers.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/components/search/tests/xpcshell/test_identifiers.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/ */
+
+/*
+ * Test that a search engine's identifier can be extracted from the filename.
+ */
+
+"use strict";
+
+const Ci = Components.interfaces;
+const SEARCH_APP_DIR = 1;
+
+function run_test() {
+  removeMetadata();
+  removeCacheFile();
+  do_load_manifest("data/chrome.manifest");
+
+  let url  = "chrome://testsearchplugin/locale/searchplugins/";
+  Services.prefs.setCharPref("browser.search.jarURIs", url);
+  Services.prefs.setBoolPref("browser.search.loadFromJars", true);
+
+  updateAppInfo();
+
+  run_next_test();
+}
+
+add_test(function test_identifier() {
+  let engineFile = gProfD.clone();
+  engineFile.append("searchplugins");
+  engineFile.append("test-search-engine.xml");
+  engineFile.parent.create(Ci.nsIFile.DIRECTORY_TYPE, FileUtils.PERMS_DIRECTORY);
+
+  // Copy the test engine to the test profile.
+  let engineTemplateFile = do_get_file("data/engine.xml");
+  engineTemplateFile.copyTo(engineFile.parent, "test-search-engine.xml");
+
+  let search = Services.search.init(function initComplete(aResult) {
+    do_print("init'd search service");
+    do_check_true(Components.isSuccessCode(aResult));
+
+    let profileEngine = Services.search.getEngineByName("Test search engine");
+    let jarEngine = Services.search.getEngineByName("bug645970");
+
+    do_check_true(profileEngine instanceof Ci.nsISearchEngine);
+    do_check_true(jarEngine instanceof Ci.nsISearchEngine);
+
+    // An engine loaded from the profile directory won't have an identifier,
+    // because it's not built-in.
+    do_check_eq(profileEngine.identifier, null);
+
+    // An engine loaded from a JAR will have an identifier corresponding to
+    // the filename inside the JAR. (In this case it's the same as the name.)
+    do_check_eq(jarEngine.identifier, "bug645970");
+
+    removeMetadata();
+    removeCacheFile();
+    run_next_test();
+  });
+});
+