def test_len_1(self):
n1 = Node(1)
s_list = LinkedList()
s_list.add_in_tail(n1)
data = s_list.len()
res = 1
self.assertEqual(data, res)
def test_len_3(self):
n1 = Node(1)
n2 = Node(3)
n3 = Node(3)
s_list = LinkedList()
s_list.add_in_tail(n1)
s_list.add_in_tail(n2)
s_list.add_in_tail(n3)
data = s_list.len()
res = 3
self.assertEqual(data, res)
def test_len_0(self):
s_list = LinkedList()
data = s_list.len()
res = 0
self.assertEqual(data, res)