diff -r 000000000000 -r 6474c204b198 toolkit/components/crashmonitor/test/unit/test_invalid_file.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/components/crashmonitor/test/unit/test_invalid_file.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,30 @@
+/* -*- Mode: js; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Test with sessionCheckpoints.json containing invalid data
+ */
+add_task(function test_invalid_file() {
+  // Write bogus data to checkpoint file
+  let data = "1234";
+  yield OS.File.writeAtomic(sessionCheckpointsPath, data,
+                            {tmpPath: sessionCheckpointsPath + ".tmp"});
+
+  // An invalid file will cause |init| to throw an exception
+  try {
+    let status = yield CrashMonitor.init();
+    do_check_true(false);
+  } catch (ex) {
+    do_check_true(true);
+  }
+
+  // and |previousCheckpoints| will be rejected
+  try {
+    let checkpoints = yield CrashMonitor.previousCheckpoints;
+    do_check_true(false);
+  } catch (ex) {
+    do_check_true(true);
+  }
+});