diff -r 000000000000 -r 6474c204b198 xpcom/tests/TestID.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/xpcom/tests/TestID.cpp	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 4; 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/. */
+#include <stdio.h>
+#include "plstr.h"
+#include "nsID.h"
+
+static const char* const ids[] = {
+  "5C347B10-D55C-11D1-89B7-006008911B81",
+  "{5C347B10-D55C-11D1-89B7-006008911B81}",
+  "5c347b10-d55c-11d1-89b7-006008911b81",
+  "{5c347b10-d55c-11d1-89b7-006008911b81}",
+
+  "FC347B10-D55C-F1D1-F9B7-006008911B81",
+  "{FC347B10-D55C-F1D1-F9B7-006008911B81}",
+  "fc347b10-d55c-f1d1-f9b7-006008911b81",
+  "{fc347b10-d55c-f1d1-f9b7-006008911b81}",
+};
+#define NUM_IDS ((int) (sizeof(ids) / sizeof(ids[0])))
+
+int main(int argc, char** argv)
+{
+  nsID id;
+  for (int i = 0; i < NUM_IDS; i++) {
+    const char* idstr = ids[i];
+    if (!id.Parse(idstr)) {
+      fprintf(stderr, "TestID: Parse failed on test #%d\n", i);
+      return -1;
+    }
+    char* cp = id.ToString();
+    if (nullptr == cp) {
+      fprintf(stderr, "TestID: ToString failed on test #%d\n", i);
+      return -1;
+    }
+    if (0 != PL_strcmp(cp, ids[4*(i/4) + 3])) {
+      fprintf(stderr, "TestID: compare of ToString failed on test #%d\n", i);
+      return -1;
+    }
+  }
+
+  return 0;
+}