def test_unvalid_left_4levels(dummy_valid_4levels_tree):
expected = False
dummy_valid_4levels_tree.root.right.left.value = 50
actual = validate_bst(dummy_valid_4levels_tree)
assert actual == expected, 'Error on test_unvalid_left_4levels.'
def test_valid_letters():
BST = BinarySearchTree()
# level 0
BST.add('d')
# level 1
BST.add('b')
BST.add('f')
# level 2
BST.add('a')
BST.add('c')
BST.add('e')
BST.add('g')
expected = True
actual = validate_bst(BST)
assert actual == expected, 'Error on test_valid_letters.'
def test_unvalid_left_letters():
BST = BinarySearchTree()
# level 0
BST.add('d')
# level 1
BST.add('b')
BST.add('f')
# level 2
BST.add('a')
BST.add('c')
BST.add('e')
BST.add('g')
expected = False
BST.root.left.right.value = 'z'
actual = validate_bst(BST)
assert actual == expected, 'Error on test_unvalid_left_letters.'
def test_valid_empty():
expected = False
actual = validate_bst(BinarySearchTree())
assert actual == expected, 'Error on test_valid_empty.'
def test_valid_4levels(dummy_valid_4levels_tree):
expected = True
actual = validate_bst(dummy_valid_4levels_tree)
assert actual == expected, 'Error on test_valid_4levels.'