def test_pre_order():
tree = BinarySearchTree()
tree.add('A')
tree.add('B')
tree.add('C')
actual = tree.pre_order()
excepted = ['A', 'B', 'C']
assert actual == excepted
def test_pre_order():
fruits = BinarySearchTree()
fruits.add('bananas')
fruits.add('apples')
fruits.add('carrots')
fruits.add('mango')
fruits.add('pear')
fruits.add('cake')
fruits.add('cookies')
fruits.add('beer')
fruits.add('whiskey')
expected = [
'bananas', 'apples', 'beer', 'cake', 'carrots', 'cookies', 'mango',
'pear', 'whiskey'
]
actual = fruits.pre_order()
assert expected == actual