def test_add(self):
bst = BinarySearchTree()
bst.add(7)
self.assertEqual(bst.root.value, 7)
self.assertIsNone(bst.root.left)
self.assertIsNone(bst.root.right)
bst.add(4)
self.assertIsNotNone(bst.root.left)
self.assertEqual(bst.root.left.value, 4)
bst.add(10)
self.assertIsNotNone(bst.root.right)
self.assertEqual(bst.root.right.value, 10)
bst.add(6)
self.assertEqual(bst.root.left.right.value, 6)
second = root
prev = root
first, second, prev = traverse(root.right, first, second, prev)
return first, second, prev
if __name__ == "__main__":
bst = BinarySearchTree.from_array([1, 4, 5, 7, 8, 9, 10])
print bst
bst.root.left.value, bst.root.right.left.value = bst.root.right.left.value, bst.root.left.value
print bst
fix_bst(bst)
print bst
print
bst = BinarySearchTree()
bst.add(0)
bst.root.left = BinaryTreeNode(1)
print bst
fix_bst(bst)
print bst
print
bst = BinarySearchTree()
bst.add(2)
bst.root.left = BinaryTreeNode(1)
bst.root.left.right = BinaryTreeNode(3)
print bst
fix_bst(bst)
print bst
