public void DFSBinarySearchTreePreOrderRecursiveTest()
{
var binarySearchTree = new BinarySearchTreeKey();
binarySearchTree.Add("4");
binarySearchTree.Add("2");
binarySearchTree.Add("6");
binarySearchTree.Add("1");
binarySearchTree.Add("3");
binarySearchTree.Add("5");
binarySearchTree.Add("7");
Assert.Equal(new [] { "4", "2", "1", "3", "6", "5", "7" }, DFS.DFSBinarySearchTreePreOrderRecursive(binarySearchTree.Root));
}