class Stack:
"""
An implementation for the Stack data structure
using a linked list.
"""
def __init__(self, item=None):
self.linked_list = LinkedList(item)
def push(self, item):
"""Pushes an element onto the top of the stack"""
self.linked_list.insert_at_head(item)
def peek(self):
"""Gets and returns an element from the top of the stack"""
return self.linked_list.get_head_item()
def pop(self):
"""Removes and returns the element on top of the stack"""
return self.linked_list.delete_head()
def clear(self):
"""Removes all the elements form the stack"""
self.linked_list.clear()
def get_size(self):
"""Returns the size of the stack"""
return self.linked_list.size
def test_get_head_with_item(self):
linked_list = LinkedList("Bob")
item = linked_list.get_head_item()
self.assertIsNotNone(item)
self.assertEqual(item, "Bob")
class TestSinglyLinkedList(unittest.TestCase):
def setUp(self):
self.linked_list = LinkedList()
def test_empty_init(self):
self.assertEqual(self.linked_list.size, 0)
self.assertIsNone(self.linked_list.head)
self.assertIsNone(self.linked_list.tail)
def test_init_with_item(self):
linked_list = LinkedList("Bob")
self.assertEqual(linked_list.size, 1)
self.assertIsNotNone(linked_list.head)
self.assertIsNotNone(linked_list.tail)
self.assertEqual(linked_list.head, linked_list.tail)
def test_insert_at_head(self):
initial_size = self.linked_list.size
self.linked_list.insert_at_head("Tom")
self.assertIsNotNone(self.linked_list.head)
self.assertEqual(self.linked_list.size, initial_size + 1)
self.assertEqual(self.linked_list.head.item, "Tom")
def test_insert_at_tail(self):
initial_size = self.linked_list.size
self.linked_list.insert_at_tail("Bob is your uncle")
self.assertEqual(self.linked_list.tail.item, "Bob is your uncle")
self.assertIsNotNone(self.linked_list.tail)
self.assertEqual(self.linked_list.size, initial_size + 1)
empty_linked_list = LinkedList()
empty_initial_size = empty_linked_list.size
empty_linked_list.insert_at_tail("Bob")
self.assertIsNotNone(empty_linked_list.head)
self.assertIsNotNone(empty_linked_list.tail)
self.assertEqual(empty_linked_list.size, empty_initial_size + 1)
def test_get_head_item_with_no_head(self):
item = self.linked_list.get_head_item()
self.assertIsNone(item)
def test_get_head_with_item(self):
linked_list = LinkedList("Bob")
item = linked_list.get_head_item()
self.assertIsNotNone(item)
self.assertEqual(item, "Bob")
def test_get_tail_item(self):
empty_linked_list = LinkedList()
empty_item = empty_linked_list.get_tail_item()
self.assertIsNone(empty_item)
linked_list = LinkedList("Bob")
item = linked_list.get_tail_item()
self.assertIsNotNone(item)
def test_get_item_at_index(self):
self.linked_list.insert_at_tail("Adrian")
self.linked_list.insert_at_tail("Bob")
self.linked_list.insert_at_tail("Chris")
item = self.linked_list.get_item_at_index(2)
self.assertEqual(item, "Chris")
with self.assertRaises(IndexError):
new_item = self.linked_list.get_item_at_index(5)
def test_search_for_item(self):
linked_list = LinkedList("Bob")
linked_list.insert_at_tail("Kim")
linked_list.insert_at_tail("Jim")
linked_list.insert_at_tail("Max")
result = linked_list.search_for_item("Max")
self.assertEqual(result, (3, "Max"))
empty_result = linked_list.search_for_item("Adrian")
self.assertIsNone(empty_result)
def test_search_for_all_item(self):
linked_list = LinkedList("Bob")
linked_list.insert_at_tail("Kim")
linked_list.insert_at_tail("Bob")
linked_list.insert_at_tail("Bob")
result = linked_list.search_for_all_item("Bob")
self.assertEqual(len(result), 3)
def test_delete_head(self):
self.linked_list.insert_at_head("Bob")
initial_size = self.linked_list.size
deleted_item = self.linked_list.delete_head()
self.assertEqual(self.linked_list.size, initial_size - 1)
self.assertEqual(deleted_item, "Bob")
self.assertIsNone(self.linked_list.head)
self.assertIsNone(self.linked_list.tail)
another_deleted_item = self.linked_list.delete_head()
self.assertIsNone(another_deleted_item)
new_linked_list = LinkedList("Adrian")
new_linked_list.insert_at_head("Bob")
new_deleted_item = new_linked_list.delete_head()
self.assertEqual(new_deleted_item, "Bob")
self.assertEqual(new_linked_list.tail.item, "Adrian")
self.assertEqual(new_linked_list.head.item, "Adrian")
def test_delete_tail(self):
self.linked_list.insert_at_tail("Bob")
self.linked_list.insert_at_tail("Jim")
self.linked_list.insert_at_tail("Ryan")
self.linked_list.insert_at_tail("Tim")
initial_size = self.linked_list.size
deleted_item = self.linked_list.delete_tail()
self.assertEqual(self.linked_list.size, initial_size - 1)
self.assertEqual(deleted_item, "Tim")
empty_linked_list = LinkedList()
empty_item = empty_linked_list.delete_tail()
self.assertIsNone(empty_item)
def test_delete_at_index(self):
self.linked_list.insert_at_tail("Adam")
self.linked_list.insert_at_tail("Bob")
self.linked_list.insert_at_tail("Chris")
self.linked_list.insert_at_tail("Dylan")
initial_size = self.linked_list.size
deleted_item = self.linked_list.delete_item_at_index(3)
self.assertEqual(self.linked_list.size, initial_size - 1)
self.assertEqual(deleted_item, "Dylan")
with self.assertRaises(IndexError):
self.linked_list.delete_item_at_index(5)
with self.assertRaises(ValueError):
self.linked_list.delete_item_at_index("Bla")
def test_clear(self):
self.linked_list.insert_at_tail("Adam")
self.linked_list.insert_at_tail("Bob")
self.linked_list.insert_at_tail("Chris")
self.linked_list.insert_at_tail("Dylan")
self.linked_list.insert_at_tail("Erin")
self.assertEqual(self.linked_list.size, 5)
self.linked_list.clear()
self.assertEqual(self.linked_list.size, 0)
