public void TestCompareTo()
{
RedBlackTree <int, string> tree1 = GetTestTree();
RedBlackTree <int, string> tree2 = new RedBlackTree <int, string>();
Assert.AreEqual(tree1.CompareTo(tree2), 1);
Assert.AreEqual(tree2.CompareTo(tree1), -1);
Assert.AreEqual(tree1.CompareTo(tree1), 0);
Assert.AreEqual(tree1.CompareTo(new object()), -1);
}