def test_4(self):
""" test popleft() removes node from front (left) """
d = Dequeue()
n1 = Node(1)
n2 = Node(2)
d.append(n1)
d.append(n2)
d.popleft()
self.assertEqual(d.head._value, 2)
def test_7(self):
""" test popleft() returns node removed from front (left) """
d = Dequeue()
n1 = Node(1)
n2 = Node(2)
d.append(n1)
d.append(n2)
self.assertEqual(d.popleft()._value, 1)
def test_6(self):
""" test popleft() returns exception if list is empty """
d = Dequeue()
self.assertEqual(d.popleft(), "Dequeue is empty")