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test_LinkedLists.py
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import pytest
from Implementations.LinkedLists import Node, SinglyLL
class TestNode:
def test_repr(self) -> None:
a = Node("a")
b = Node()
assert repr(a) == "Node(a)"
assert repr(b) == "Node(None)"
def test_equality(self) -> None:
node = Node()
node_1 = Node(1)
node_2 = Node(2)
node_a = Node("a")
assert node == Node()
assert node_1 == Node(1)
assert node_1 != 1
assert node_1 != node_a
assert node_1 != node_2
class TestSinglyLL:
def test_repr(self) -> None:
empty_sll = repr(SinglyLL())
filled_sll = repr(SinglyLL([1, "a", 2.5]))
assert (
empty_sll == ""
), f"repr output ('{empty_sll}') doesn't match expected output ('')"
assert (
filled_sll == "1->a->2.5"
), f"repr output ('{filled_sll}') doesn't match expected output ('1->a->2.5')"
def test_len(self) -> None:
lst = SinglyLL([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
assert len(lst) == 10, f"list length should be 10, not {len(lst)}"
lst.pop()
assert len(lst) == 9, f"list length should be 9, not {len(lst)}"
lst.insert(10)
assert len(lst) == 10, f"list length should be 10, not {len(lst)}"
empty_lst = SinglyLL()
assert len(empty_lst) == 0, f"list length should be 0, not {len(lst)}"
empty_lst.insert(1)
assert len(empty_lst) == 1, f"list length should be 1, not {len(lst)}"
empty_lst.pop()
assert len(empty_lst) == 0, f"list length should be 0, not {len(lst)}"
def test_insert(self) -> None:
# Non circular list:
lst = SinglyLL(circular=False)
assert (
lst.head is lst.tail is None
), f"head and tail must be None, not {lst.head} or {lst.tail}"
lst.insert("a")
assert (
lst.head == lst.tail == Node("a")
), f"head and tail must be Node(a), not {lst.head} or {lst.tail}"
lst.insert("b")
assert lst.head == Node("a"), f"head must be Node(a), not {lst.head}"
assert lst.tail == Node("b"), f"tail must be Node(b), not {lst.tail}"
assert (
lst.head.next == lst.tail
), f"head.next must be {lst.tail}, not {lst.head.next}"
assert lst.tail.next == None, f"tail.next must be None, not {lst.tail.next}"
lst.insert(1, 0)
assert lst.head == Node(1), f"head must be Node(1), not {lst.head}"
assert lst.head.next == Node("a"), f"head must be Node(a), not {lst.head}"
lst.insert(5, 2)
assert (
lst[-2].next == lst.tail
), f"inserted_node.next must be {lst.tail}, not {lst[-2].next}"
lst.insert(-5.5, 1)
assert lst.head.next == Node(
-5.5
), f"head.next must be Node(-5.5), not {lst.head.next}"
for i in [2.5, -7.8, "a"]:
error_msg = f"Invalid type {type(i)}. Index must be int"
with pytest.raises(TypeError, match=error_msg):
lst.insert("foo", i)
for i in [-1, -10, 6, 12]:
error_msg = (
f"index out of bound, please specify an index between 0 and {len(lst)}"
)
with pytest.raises(IndexError, match=error_msg):
lst.insert("foo", i)
# Circular list:
circular_lst = SinglyLL(circular=True)
for i in [1, 2, 3]:
circular_lst.insert(i)
assert (
circular_lst.tail.next == circular_lst.head
), f"tail.next must be the list head ({lst.head}, not {lst.tail.next})"
def test_pop(self) -> None:
lst = SinglyLL()
assert (
lst.pop() == lst
), "popping from an empty list should return the same list without modification"
lst.insert(1).pop(0)
assert (
lst.head is lst.tail is None
), f"lst must be empty after pop, instead head is {lst.head} and tail is {lst.tail}"
for i in [1, 2, 3, 4, 5]:
lst.insert(i)
lst.pop(0)
assert lst.head == Node(2), f"new head node must be Node(2), not {lst.head}"
lst.pop()
assert lst.tail == Node(4), f"new tail node must be Node(4), not {lst.tail}"
assert lst.tail.next is None, f"tail.next should be None, not {lst.tail.next}"
lst.pop(1)
assert lst.head.next == lst.tail
for i in [2.5, -7.8, "a"]:
error_msg = f"Invalid type {type(i)}. Index must be int"
with pytest.raises(TypeError, match=error_msg):
lst.pop(i)
for i in [2, 3, 4, 5]:
error_msg = f"Index out of bound, please specify an index between 0 and {len(lst)-1}"
with pytest.raises(IndexError, match=error_msg):
lst.pop(i)
# Test circular list:
circular_lst = SinglyLL([1, 2, 3, 4, 5], circular=True)
circular_lst.pop(0)
assert circular_lst.head == Node(
2
), f"new head node must be Node(2), not {circular_lst.head}"
circular_lst.pop()
assert circular_lst.tail == Node(
4
), f"new tail node must be Node(4), not {circular_lst.tail}"
assert (
circular_lst.tail.next == circular_lst.head
), f" tail.next should refer to head ({circular_lst.head}, not {circular_lst.tail.next})"
def test_remove(self) -> None:
lst = SinglyLL()
assert (
lst.remove(1) == lst
), "removing from an empty list should return the same list without modification"
lst = SinglyLL([1])
lst.remove(1)
assert (
lst.head is lst.tail is None
), f"empty list head and tail must be None, not {lst.head} or {lst.tail}"
lst = SinglyLL([1, 2, 3, 4, 5])
lst.remove(1)
assert lst.head == Node(2), f"new head node must be Node(2), not {lst.head}"
lst.remove(5)
assert lst.tail == Node(4), f"new tail node must be Node(4), not {lst.tail}"
assert lst.tail.next is None, f"tail.next should be None, not {lst.tail.next}"
lst.remove(3)
assert len(lst) == 2, f"list length should be 2, not {len(lst)}"
for i in [1, 3, 5, "a", 12, -2, -4]:
error_msg = f"'{i}' does not exists in the list."
with pytest.raises(ValueError, match=error_msg):
lst.remove(i)
# Test circular list:
circular_lst = SinglyLL([1, 2, 3, 4, 5], circular=True)
circular_lst.remove(1)
assert circular_lst.head == Node(
2
), f"new head node must be Node(2), not {circular_lst.head}"
circular_lst.remove(5)
assert circular_lst.tail == Node(
4
), f"new tail node must be Node(4), not {circular_lst.tail}"
assert (
circular_lst.tail.next == circular_lst.head
), f" tail.next should refer to head ({circular_lst.head}, not {circular_lst.tail.next})"
def test_delete(self) -> None:
lst = SinglyLL([1, 2, 3, 4, 5, 6])
circular_lst = SinglyLL([1, 2, 3, 4, 5, 6, 7, 8])
lst.delete()
circular_lst.delete()
assert (
lst.head is lst.tail is None
), f"list head and tail must be None, not {lst.head} or {lst.tail}"
assert len(lst) == 0, f"list length must be 0, not {len(lst)}"
assert (
circular_lst.head is circular_lst.tail is None
), f"list head and tail must be None, not {circular_lst.head} or {circular_lst.tail}"
assert len(circular_lst) == 0, f"list length must be 0, not {len(circular_lst)}"
def test_iteration(self) -> None:
elements = [1, 2, 3, 4, 5, 6, 7, 8]
lst = SinglyLL(elements)
circular_lst = SinglyLL(elements)
for node, val in zip(lst, elements):
assert node.data == val
for node, val in zip(circular_lst, elements):
assert node.data == val
def test_getitem(self) -> None:
vals = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
lst = SinglyLL(vals)
circular_lst = SinglyLL(vals, circular=True)
for l in [lst, circular_lst]:
for i in range(-10, 10):
assert l[i].data == vals[i]
for i in range(10, 15):
error_msg = f"Index out of bound, please specify an index between 0 and {len(lst)-1}"
with pytest.raises(IndexError, match=error_msg):
l[i]
for i in [1.5, -8.5, -12.5, "a"]:
error_msg = f"Invalid type {type(i)}. Index must be int"
with pytest.raises(TypeError, match=error_msg):
l[i]
def test_contains(self) -> None:
vals = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
lst = SinglyLL(vals)
circular_lst = SinglyLL(vals, circular=True)
for l in [lst, circular_lst]:
for i in vals:
assert i in l
for i in [-1, -2, "a", "b", "c"]:
assert i not in l