diff -r 000000000000 -r 6474c204b198 xpcom/tests/unit/test_ioutil.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/tests/unit/test_ioutil.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,33 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* 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/. */
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+const Cr = Components.results;
+
+const util = Cc["@mozilla.org/io-util;1"].getService(Ci.nsIIOUtil);
+
+function run_test()
+{
+    try {
+        util.inputStreamIsBuffered(null);
+        do_throw("inputStreamIsBuffered should have thrown");
+    } catch (e) {
+        do_check_eq(e.result, Cr.NS_ERROR_INVALID_POINTER);
+    }
+
+    try {
+        util.outputStreamIsBuffered(null);
+        do_throw("outputStreamIsBuffered should have thrown");
+    } catch (e) {
+        do_check_eq(e.result, Cr.NS_ERROR_INVALID_POINTER);
+    }
+
+    var s = Cc["@mozilla.org/io/string-input-stream;1"]
+              .createInstance(Ci.nsIStringInputStream);
+    var body = "This is a test";
+    s.setData(body, body.length);
+    do_check_eq(util.inputStreamIsBuffered(s), true);
+}