def test_breadth_traversal():
tree = BinarySearchTree()
queue = Queue()
tree.add(5)
tree.add(4)
tree.add(10)
tree.add(2)
assert tree.breadth_first(tree) == [5, 4, 10, 2]
assert tree.breadth_first(tree) != [5, 4, 10, 3]
def test_reads_four():
tree = BinarySearchTree()
tree.add(67)
tree.add(62)
tree.add(65)
tree.add(90)
assert tree.root.data == 67
assert tree.root.left.data == 62
assert tree.root.right.data == 90
assert tree.breadth_first() == [67, 62, 90, 65]
def test_exists():
tree = BinarySearchTree()
assert tree.breadth_first() == []
def test_reads_one():
tree = BinarySearchTree()
tree.add(67)
assert tree.breadth_first() == [67]
