def test_can_use_add_method_to_add_to_tree():
tree = BinarySearchTree()
tree.add(3)
tree.add(6)
tree.add(4)
actual = tree.preorder()
expected = [3, 6, 4]
assert actual == expected
def test_preorder():
"""Successfully returns an array of preordered values from a binary tree"""
tree = BinarySearchTree()
tree.add('D')
tree.add('B')
tree.add('A')
tree.add('C')
tree.add('F')
tree.add('E')
assert tree.preorder() == ['D', 'B', 'A', 'C', 'F', 'E']
def test_preorder():
"""Successfully returns an empty array from an empty binary tree"""
tree = BinarySearchTree()
assert tree.preorder() == []
BST = BinarySearchTree(15)
BST.insert(9)
BST.insert(6)
BST.insert(12)
BST.insert(4)
BST.insert(2)
BST.insert(5)
BST.insert(8)
BST.insert(10)
BST.insert(14)
BST.insert(30)
BST.insert(19)
BST.insert(17)
BST.insert(18)
BST.insert(20)
BST.insert(35)
BST.insert(32)
BST.insert(36)
print("===Preorder===")
BST.preorder()
print("\n\n---------remove30-----------\n\n")
BST.remove(30)
BST.remove(17)
print("===Preorder===")
BST.preorder()
print("\n===size, depth===\n")
print("size : {}".format(BST.size()))
print("depth : {}".format(BST.depth()))
