def test_10(self):
""" remove by value, return an exception if doesn't exist """
dl = DoubleLinkedList()
n1 = Node(5)
n2 = Node(3)
n3 = Node(6)
dl.append(n1)
dl.append(n2)
dl.append(n3)
dl.remove(7)
self.assertEqual(dl.remove(7), "Node does not exist!")
def test_9(self):
""" remove by value, removed node's next now next of removed node's prev """
dl = DoubleLinkedList()
n1 = Node(5)
n2 = Node(3)
n3 = Node(6)
dl.append(n1)
dl.append(n2)
dl.append(n3)
dl.remove(3)
self.assertEqual(dl.head._next._value, 6)
def test_8(self):
"""test to remove tail by using remove method"""
n1 = Node('A')
n2 = Node('B')
n3 = Node('C')
dl = DoubleLinkedList()
dl.append(n1)
dl.append(n2)
dl.append(n3)
dl.remove('C') #this removes C so tail should become BaseException
self.assertEqual(dl.tail._value, 'B')
class DoublyLinkedListCase(unittest.TestCase):
dll = None
def setUp(self):
self.dll = DoubleLinkedList()
def test_init(self):
self.assertIsNone(self.dll._head, "Initial HEAD should be None")
self.assertIsNone(self.dll._tail, "Initial TAIL should be None")
self.assertEqual(0, len(self.dll), "Initial length should be zero")
def test_append_left(self):
self.dll.append_left(1)
self.assertEqual(1, self.dll._head.value,
"Expected value 1 in first Node")
self.assertEqual(1, len(self.dll), "Length should be 1")
self.assertEqual(self.dll._head, self.dll._tail,
"HEAD should equal TAIL")
prev_added_node = self.dll._head
count = 1
for i in range(5):
self.dll.append_left(i)
count += 1
self.assertEqual(i, self.dll._head.value,
"Expected value " + str(i) + " in first Node")
self.assertEqual(
prev_added_node.value, self.dll._head.next.value,
"Expected value" + str(prev_added_node.value) + "in next Node")
self.assertEqual(count, len(self.dll),
"Length should be " + str(count))
self.assertEqual(prev_added_node, self.dll._head.next,
"First node should point to second node")
self.assertEqual(self.dll._head, prev_added_node.prev,
"Second node should point to this node")
prev_added_node = self.dll._head
def test_append(self):
self.dll.append(1)
self.assertEqual(self.dll._head.value, 1,
"Expected value 1 in first Node")
self.assertEqual(len(self.dll), 1, "Length should be 1")
self.assertEqual(self.dll._head, self.dll._tail,
"HEAD should equal TAIL")
prev_added_node = self.dll._tail
count = 1
for i in range(5):
self.dll.append(i)
count += 1
self.assertEqual(self.dll._tail.value, i,
"Expected value " + str(i) + " in last Node")
self.assertEqual(
self.dll._tail.prev.value, prev_added_node.value,
"Expected value" + str(prev_added_node.value) +
"in previous Node")
self.assertEqual(len(self.dll), count,
"Length should be " + str(count))
self.assertEqual(self.dll._tail.prev, prev_added_node,
"Added node should point to second last node")
self.assertEqual(prev_added_node.next, self.dll._tail,
"Second Last node should point to added node")
prev_added_node = self.dll._tail
def test_pop(self):
count = 5
for i in range(count):
self.dll.append(i)
self.assertEqual(count, len(self.dll),
"Length should be " + str(count))
# Pop from a dll with > 1 elements
for i in range(count, 1, -1):
value = self.dll.pop()
count -= 1
self.assertEqual(count, len(self.dll),
"Length should be " + str(count))
self.assertEqual(i - 1, value, "Value should equal " + str(i - 1))
self.assertIsNone(self.dll._tail.next, "TAIL.next should be None")
# Pop from a dll with 1 element
self.assertEqual(count, len(self.dll), "Length should be " + str(1))
value = self.dll.pop()
self.assertEqual(0, len(self.dll), "Length should be " + str(0))
self.assertEqual(0, value, "Value should equal " + str(0))
self.assertIsNone(self.dll._head, "HEAD should be None")
self.assertIsNone(self.dll._tail, "TAIL should be None")
# Pop from an empty dll
node = self.dll.pop()
self.assertIsNone(node, "Popping an empty dll returns None")
def test_pop_left(self):
n = count = 5
for i in range(count):
self.dll.append(i)
self.assertEqual(count, len(self.dll),
"Length should be " + str(count))
# Pop_left from a dll with > 1 elements
for i in range(count - 1):
value = self.dll.pop_left()
count -= 1
self.assertEqual(count, len(self.dll),
"Length should be " + str(count))
self.assertEqual(i, value, "Value should equal " + str(i))
self.assertEqual(i + 1, self.dll._head.value,
"Next value should equal " + str(i + 1))
# Pop from a dll with 1 element
self.assertEqual(count, len(self.dll), "Length should be " + str(1))
value = self.dll.pop_left()
self.assertEqual(0, len(self.dll), "Length should be " + str(0))
self.assertEqual(n - 1, value, "Value should equal " + str(n - 1))
self.assertIsNone(self.dll._head, "HEAD should be None")
self.assertIsNone(self.dll._tail, "TAIL should be None")
# Pop from an empty dll
node = self.dll.pop_left()
self.assertIsNone(node, "Popping an empty dll returns None")
def test_find(self):
n = 5
for i in range(n):
self.dll.append(i)
self.assertEqual(3, self.dll.find(3).value, "Can find value of 3")
self.assertIsNone(self.dll.find(10),
"Cannot find a node with a value of 10")
def test_insert_after(self):
n, m = 5, 3
for i in range(n):
self.dll.append(i)
node = self.dll.find(m)
node2 = node.next
self.dll.insert_after(node, 10)
self.assertEqual(10, node.next.value,
"Value of 10 is inserted after given node")
self.assertEqual(node.next, node2.prev,
"New node is inserted before 'node2")
expected = [i for i in range(n)]
expected.insert(m + 1, 10)
count = 0
for i in self.dll:
self.assertEqual(expected[count], i)
count += 1
# Insert after TAIL
self.dll.insert_after(self.dll._tail, 11)
self.assertEqual(11, self.dll._tail.value,
"Value of 11 is inserted at TAIL")
self.assertIsNone(self.dll._tail.next, "HEAD.next is None")
def test_insert_before(self):
n, m = 5, 3
for i in range(n):
self.dll.append(i)
node = self.dll.find(m)
node2 = node.prev
self.dll.insert_before(node, 10)
self.assertEqual(10, node.prev.value,
"Value of 10 is inserted before 'node'")
self.assertEqual(node2.next, node.prev,
"New node is inserted after 'node2")
expected = [i for i in range(n)]
expected.insert(m, 10)
count = 0
for i in self.dll:
self.assertEqual(expected[count], i)
count += 1
# Insert before HEAD
self.dll.insert_before(self.dll._head, 11)
self.assertEqual(11, self.dll._head.value,
"Value of 11 is inserted at HEAD")
self.assertIsNone(self.dll._head.prev, "HEAD.prev is None")
def test_remove(self):
n = 5
for i in range(n):
self.dll.append(i)
# Remove existing value
self.dll.remove(2)
self.assertEqual(n - 1, len(self.dll),
"Length should be " + str(n - 1))
self.assertIsNone(self.dll.find(2),
"There should be no value of 2 in the dll")
# print(self.dll)
# Remove non existing value
self.dll.remove(-1)
self.assertEqual(n - 1, len(self.dll),
"Length should still be" + str(n - 1))
def test_delete(self):
n = 5
for i in range(n):
self.dll.append(i)
# Delete existing value
node = self.dll.find(2)
prev = node.prev
next = node.next
val = self.dll.delete(node)
self.assertEqual(2, val, "Returned value should be 2")
self.assertEqual(n - 1, len(self.dll),
"Length should be " + str(n - 1))
self.assertIsNone(self.dll.find(2),
"There should be no value of 2 in the dll")
self.assertEqual(next, prev.next, "Links previous to next node")
self.assertEqual(prev, next.prev, "Links next node to previous")
# Delete non existing value
node = Node(2)
val = self.dll.delete(node)
self.assertIsNone(val, "Should return None")
self.assertEqual(n - 1, len(self.dll),
"Length should still be " + str(n - 1))
# print(self.dll)
# Delete first node
node = self.dll.find(0)
next = node.next
self.dll.delete(node)
self.assertEqual(len(self.dll), n - 2,
"Length should be " + str(n - 2))
self.assertIsNone(self.dll.find(0),
"There should be no value of 0 in the dll")
for elem in self.dll:
self.assertEqual(next.value, elem,
"Next should now be at the HEAD")
break
# print(self.dll)
# Delete last node
# print(self.dll)
# node = self.dll.find(n - 1)
def test_contains(self):
n = 5
for i in range(n):
self.dll.append(i)
# 0 - 4 should be contained in dll
for i in range(n):
self.assertTrue(i in self.dll, "DLL should contain " + str(i))
# Should not contain n
self.assertFalse(n in self.dll, "DLL should not contain" + str(n))