diff -r 000000000000 -r 6474c204b198 xpcom/tests/unit/test_bug478086.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/tests/unit/test_bug478086.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,25 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/  */
+
+function run_test() {
+  var nsILocalFile = Components.interfaces.nsILocalFile;
+  var root = Components.classes["@mozilla.org/file/local;1"].
+              createInstance(nsILocalFile);
+
+  // copied from http://mxr.mozilla.org/mozilla-central/source/image/test/unit/test_imgtools.js#135
+  // nsIXULRuntime.OS doesn't seem to be available in xpcshell, so we'll use
+  // this as a kludgy way to figure out if we're running on Windows.
+  var isWindows = ("@mozilla.org/windows-registry-key;1" in Components.classes);
+  if (isWindows) {
+    root.initWithPath("\\\\.");
+  } else {
+    return; // XXX disabled, since this causes intermittent failures on Mac (bug 481369).
+    root.initWithPath("/");
+  }
+  var drives = root.directoryEntries;
+  do_check_true(drives.hasMoreElements());
+  while (drives.hasMoreElements()) {
+    var newPath = drives.getNext().QueryInterface(nsILocalFile).path;
+    do_check_eq(newPath.indexOf("\0"), -1);
+  }
+}