test: add test case for linked-list version of is-palindrome

data_structures/linked_list/tests/test_is_palindrome.py

@@ -0,0 +1,98 @@
+from dataclasses import dataclass
+from typing import Any
+
+import pytest
+
+from data_structures.linked_list.is_palindrome import (
+    is_palindrome,
+    is_palindrome_dict,
+    is_palindrome_stack,
+)
+
+
+@dataclass
+class Node:
+    val: Any
+    next: "Node" = None
+
+
+@pytest.fixture
+def single_char() -> Node:
+    return Node("a")
+
+
+@pytest.fixture
+def kayake() -> Node:
+    e = Node("e")
+    k = Node("k", e)
+    a = Node("a", k)
+    y = Node("y", a)
+    a = Node("a", y)
+    k = Node("k", a)
+    return k
+
+
+@pytest.fixture
+def racecar() -> Node:
+    r = Node("r")
+    a = Node("a", r)
+    c = Node("c", a)
+    e = Node("e", c)
+    c = Node("c", e)
+    a = Node("a", c)
+    r = Node("r", a)
+    return r
+
+
+@pytest.fixture
+def stats() -> Node:
+    s = Node("s")
+    t = Node("t", s)
+    a = Node("a", t)
+    t = Node("t", a)
+    s = Node("s", t)
+    return s
+
+
+@pytest.fixture
+def computer() -> Node:
+    r = Node("r")
+    e = Node("e", r)
+    t = Node("t", e)
+    u = Node("u", t)
+    p = Node("p", u)
+    m = Node("m", p)
+    o = Node("o", m)
+    c = Node("c", o)
+    return c
+
+
+def test_is_palindrome_correct_result(racecar, stats, computer, kayake, single_char):
+    assert is_palindrome(None)
+    assert is_palindrome(single_char)
+    assert is_palindrome(racecar)
+    assert is_palindrome(stats)
+    assert not is_palindrome(kayake)
+    assert not is_palindrome(computer)
+
+
+def test_is_palindrome_dict_correct_result(
+    racecar, stats, computer, kayake, single_char
+):
+    assert is_palindrome_dict(None)
+    assert is_palindrome_dict(single_char)
+    assert is_palindrome_dict(racecar)
+    assert is_palindrome_dict(stats)
+    assert not is_palindrome_dict(kayake)
+    assert not is_palindrome_dict(computer)
+
+
+def test_is_palindrome_stack_correct_result(
+    racecar, stats, computer, kayake, single_char
+):
+    assert is_palindrome_stack(None)
+    assert is_palindrome_stack(single_char)
+    assert is_palindrome_stack(racecar)
+    assert is_palindrome_stack(stats)
+    assert not is_palindrome_stack(kayake)
+    assert not is_palindrome_stack(computer)