def test_breadth_first_mostly_left_side_nodes(self):
bt = BinaryTree()
bt.root = BinaryTreeNode(1)
bt.root.left = BinaryTreeNode(2)
bt.root.right = BinaryTreeNode(3)
bt.root.left.left = BinaryTreeNode(4)
bt.root.left.right = BinaryTreeNode(5)
bt.root.right.right = BinaryTreeNode(7)
bt.root.left.left.left = BinaryTreeNode(6)
bt.root.left.left.left.left = BinaryTreeNode(8)
result, depth = bt.breadth_first()
self.assertEqual(result, [1, 2, 3, 4, 5, 7, 6, 8])
self.assertEqual(depth, 4)
def test_breadth_first_empty_tree(self):
bt = BinaryTree()
result, depth = bt.breadth_first()
self.assertEqual(result, [])
self.assertEqual(depth, 0)
