diff -r 000000000000 -r 6474c204b198 toolkit/mozapps/extensions/test/xpinstall/browser_signed_tampered.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/mozapps/extensions/test/xpinstall/browser_signed_tampered.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,33 @@
+// ----------------------------------------------------------------------------
+// Tests installing a signed add-on that has been tampered with after signing.
+function test() {
+  Harness.installConfirmCallback = confirm_install;
+  Harness.downloadFailedCallback = download_failed;
+  Harness.installsCompletedCallback = finish_test;
+  Harness.setup();
+
+  var pm = Services.perms;
+  pm.add(makeURI("http://example.com/"), "install", pm.ALLOW_ACTION);
+
+  var triggers = encodeURIComponent(JSON.stringify({
+    "Tampered Signed XPI": TESTROOT + "signed-tampered.xpi"
+  }));
+  gBrowser.selectedTab = gBrowser.addTab();
+  gBrowser.loadURI(TESTROOT + "installtrigger.html?" + triggers);
+}
+
+function confirm_install(window) {
+  ok(false, "Should not offer to install");
+}
+
+function download_failed(install) {
+  is(install.error, AddonManager.ERROR_CORRUPT_FILE, "Install should fail");
+}
+
+function finish_test(count) {
+  is(count, 0, "No add-ons should have been installed");
+  Services.perms.remove("example.com", "install");
+
+  gBrowser.removeCurrentTab();
+  Harness.finish();
+}