def test_five_nodes():
t = Tree()
t.right = Tree()
t.right.right = Tree()
t.left = Tree()
t.left.left = Tree()
assert_that(max_distance(t), equal_to(4))
def test_eight_nodes_unbalanced():
t = Tree()
t.right = Tree()
t.right.left = Tree()
t.right.left.left = Tree()
t.right.left.left.left = Tree()
t.right.right = Tree()
t.right.right.right = Tree()
t.right.right.right.right = Tree()
assert_that(max_distance(t), equal_to(6))
def test_two_nodes_left():
t = Tree()
t.left = Tree()
assert_that(max_distance(t), equal_to(1))
def test_four_nodes_unbalanced_spread():
t = Tree()
t.right = Tree()
t.right.right = Tree()
t.left = Tree()
assert_that(max_distance(t), equal_to(3))
def test_single_node():
t = Tree()
assert_that(max_distance(t), equal_to(0))