diff --git a/mozilla/xpcom/tests/TestVoidBTree.cpp b/mozilla/xpcom/tests/TestVoidBTree.cpp
new file mode 100644
index 00000000000..e02939a4d33
--- /dev/null
+++ b/mozilla/xpcom/tests/TestVoidBTree.cpp
@@ -0,0 +1,245 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * The contents of this file are subject to the Mozilla Public License
+ * Version 1.1 (the "MPL"); you may not use this file except in
+ * compliance with the MPL.  You may obtain a copy of the MPL at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the MPL is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the MPL
+ * for the specific language governing rights and limitations under the
+ * MPL.
+ *
+ * The Initial Developer of this code under the MPL is Netscape
+ * Communications Corporation.  Portions created by Netscape are
+ * Copyright (C) 1999 Netscape Communications Corporation.  All Rights
+ * Reserved.
+ *
+ * Original Author:
+ *   Chris Waterson <waterson@netscape.com>
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include "nsVoidBTree.h"
+#include "nsVoidArray.h"
+
+#define COUNT 1024
+#define POINTER(i) NS_REINTERPRET_CAST(void*, 4 + 4 * (i))
+
+static PRBool
+Equal(const nsVoidArray& aControl, const nsVoidBTree& aTest)
+{
+    if (aControl.Count() != aTest.Count()) {
+        printf("counts not equal; ");
+        return PR_FALSE;
+    }
+
+    for (PRInt32 i = aControl.Count() - 1; i >= 0; --i) {
+        if (aControl[i] != aTest[i]) {
+            printf("element %d differs; ", i);
+            return PR_FALSE;
+        }
+    }
+
+    return PR_TRUE;
+}
+
+
+static void
+CheckForwardEnumeration(const nsVoidArray& aControl, const nsVoidBTree& aTest)
+{
+    PRInt32 index = 0;
+
+    nsVoidBTree::ConstIterator last = aTest.Last();
+    for (nsVoidBTree::ConstIterator element = aTest.First(); element != last; ++element, ++index) {
+        if (*element != aControl[index]) {
+            printf("failed forward enumeration\n");
+            exit(-1);
+        }
+    }
+
+    if (index != aControl.Count()) {
+        printf("erratic termination during forward enumeration\n");
+        exit(-1);
+    }
+}
+
+static void
+CheckBackwardEnumeration(const nsVoidArray& aControl, const nsVoidBTree& aTest)
+{
+    PRInt32 index = aControl.Count();
+    nsVoidBTree::ConstIterator first = aTest.First();
+    nsVoidBTree::ConstIterator element = aTest.Last();
+
+    if (first != element) {
+        do {
+            if (*--element != aControl[--index]) {
+                printf("failed backward enumeration\n");
+                exit(-1);
+            }
+        } while (element != first);
+    }
+
+    if (index != 0) {
+        printf("erratic termination during backward enumeration\n");
+        exit(-1);
+    }
+}
+
+int main(int argc, char* argv[])
+{
+    nsVoidBTree btree;
+
+    PRInt32 i;
+
+    //----------------------------------------
+    // Tail fill
+    for (i = 0; i < COUNT; ++i)
+        btree.InsertElementAt(NS_REINTERPRET_CAST(void*, POINTER(i)), i);
+
+    for (i = 0; i < COUNT; ++i) {
+        if (btree[i] != POINTER(i)) {
+            printf("tail fill failed\n");
+            return -1;
+        }
+    }
+
+    printf("tail fill succeeded\n");
+
+    //----------------------------------------
+    // Tail empty
+    for (i = COUNT - 1; i >= 0; --i)
+        btree.RemoveElementAt(i);
+
+    if (btree.Count() != 0) {
+        printf("tail empty failed\n");
+        return -1;
+    }
+
+    printf("tail empty succeeded\n");
+
+    // N.B. no intervening Clear() to verify that we handle the re-use
+    // case.
+
+    //----------------------------------------
+    // Front fill
+    for (i = 0; i < COUNT; ++i)
+        btree.InsertElementAt(POINTER(i), 0);
+
+    for (i = 0; i < COUNT; ++i) {
+        if (btree[COUNT - (i + 1)] != POINTER(i)) {
+            printf("simple front fill failed\n");
+            return -1;
+        }
+    }
+
+    printf("front fill succeeded\n");
+
+    //----------------------------------------
+    // Front empty
+    for (i = COUNT - 1; i >= 0; --i)
+        btree.RemoveElementAt(0);
+
+    if (btree.Count() != 0) {
+        printf("front empty failed\n");
+        return -1;
+    }
+
+    printf("front empty succeeded\n");
+    fflush(stdout);
+
+    //----------------------------------------
+    // Test boundary conditions with small btree
+
+    {
+        printf("small btree boundary conditions ");
+        fflush(stdout);
+
+        nsVoidArray control;
+        btree.Clear();
+
+        CheckBackwardEnumeration(control, btree);
+        CheckForwardEnumeration(control, btree);
+
+        btree.AppendElement(POINTER(0));
+        control.AppendElement(POINTER(0));
+
+        CheckBackwardEnumeration(control, btree);
+        CheckForwardEnumeration(control, btree);
+
+        btree.AppendElement(POINTER(1));
+        control.AppendElement(POINTER(1));
+
+        CheckBackwardEnumeration(control, btree);
+        CheckForwardEnumeration(control, btree);
+
+        btree.RemoveElementAt(0);
+        btree.RemoveElementAt(0);
+        control.RemoveElementAt(0);
+        control.RemoveElementAt(0);
+
+        CheckBackwardEnumeration(control, btree);
+        CheckForwardEnumeration(control, btree);
+
+        printf("succeeded\n");
+    }
+
+    //----------------------------------------
+    // Random hammering
+
+    printf("random fill/empty: ");
+
+    for (PRInt32 iter = 10; iter >= 1; --iter) {
+        printf("%d ", iter);
+        fflush(stdout);
+
+        nsVoidArray control;
+        btree.Clear();
+
+        // Fill
+        for (i = 0; i < COUNT; ++i) {
+            PRInt32 slot = i ? rand() % i : 0;
+
+            btree.InsertElementAt(POINTER(i), slot);
+            control.InsertElementAt(POINTER(i), slot);
+
+            if (! Equal(control, btree)) {
+                printf("failed\n");
+                return -1;
+            }
+        }
+
+        // IndexOf
+        for (i = 0; i < COUNT; ++i) {
+            void* element = control[i];
+            if (btree.IndexOf(element) != i) {
+                printf("failed IndexOf at %d\n", i);
+                return -1;
+            }
+        }
+
+        // Backward enumeration
+        CheckBackwardEnumeration(control, btree);
+               
+        // Forward enumeration
+        CheckForwardEnumeration(control, btree);
+
+        // Empty
+        for (i = COUNT - 1; i >= 0; --i) {
+            PRInt32 slot = i ? rand() % i : 0;
+
+            btree.RemoveElementAt(slot);
+            control.RemoveElementAt(slot);
+
+            if (! Equal(control, btree)) {
+                printf("failed\n");
+                return -1;
+            }
+        }
+    }
+
+    printf("succeeded\n");
+
+    return 0;
+}