diff -r 000000000000 -r 6474c204b198 toolkit/mozapps/extensions/test/xpinstall/browser_enabled.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/mozapps/extensions/test/xpinstall/browser_enabled.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,20 @@
+// ----------------------------------------------------------------------------
+// Test whether an InstallTrigger.enabled is working
+function test() {
+  waitForExplicitFinish();
+
+  gBrowser.selectedTab = gBrowser.addTab();
+  gBrowser.selectedBrowser.addEventListener("load", function() {
+    gBrowser.selectedBrowser.removeEventListener("load", arguments.callee, true);
+    // Allow the in-page load handler to run first
+    executeSoon(page_loaded);
+  }, true);
+  gBrowser.loadURI(TESTROOT + "enabled.html");
+}
+
+function page_loaded() {
+  var doc = gBrowser.contentDocument;
+  is(doc.getElementById("enabled").textContent, "true", "installTrigger should have been enabled");
+  gBrowser.removeCurrentTab();
+  finish();
+}