diff -r 000000000000 -r 6474c204b198 browser/base/content/test/general/browser_bug431826.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/base/content/test/general/browser_bug431826.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,41 @@
+function test() {
+  waitForExplicitFinish();
+
+  gBrowser.selectedTab = gBrowser.addTab();
+
+  // Navigate to a site with a broken cert
+  window.addEventListener("DOMContentLoaded", testBrokenCert, true);
+  content.location = "https://nocert.example.com/";
+}
+
+function testBrokenCert() {
+  window.removeEventListener("DOMContentLoaded", testBrokenCert, true);
+
+  // Confirm that we are displaying the contributed error page, not the default
+  ok(gBrowser.contentDocument.documentURI.startsWith("about:certerror"), "Broken page should go to about:certerror, not about:neterror");
+
+  // Confirm that the expert section is collapsed
+  var expertDiv = gBrowser.contentDocument.getElementById("expertContent");
+  ok(expertDiv, "Expert content div should exist");
+  ok(expertDiv.hasAttribute("collapsed"), "Expert content should be collapsed by default");
+
+  // Tweak the expert mode pref
+  gPrefService.setBoolPref("browser.xul.error_pages.expert_bad_cert", true);
+
+  window.addEventListener("DOMContentLoaded", testExpertPref, true);
+  gBrowser.reload();
+}
+
+function testExpertPref() {
+  window.removeEventListener("DOMContentLoaded", testExpertPref, true);
+  var expertDiv = gBrowser.contentDocument.getElementById("expertContent");
+  var technicalDiv = gBrowser.contentDocument.getElementById("technicalContent");
+  ok(!expertDiv.hasAttribute("collapsed"), "Expert content should not be collapsed with the expert mode pref set");
+  ok(!technicalDiv.hasAttribute("collapsed"), "Technical content should not be collapsed with the expert mode pref set");
+
+  // Clean up
+  gBrowser.removeCurrentTab();
+  if (gPrefService.prefHasUserValue("browser.xul.error_pages.expert_bad_cert"))
+    gPrefService.clearUserPref("browser.xul.error_pages.expert_bad_cert");
+  finish();
+}