import unittest
from z_algorithm import z_function, search


class TestZ(unittest.TestCase):
    def test_empty(self):
        self.assertEqual(z_function(""), [])

    def test_single(self):
        self.assertEqual(z_function("a"), [1])

    def test_all_same(self):
        self.assertEqual(z_function("aaaa"), [4, 3, 2, 1])

    def test_ababa(self):
        self.assertEqual(z_function("ababa"), [5, 0, 3, 0, 1])

    def test_search_basic(self):
        self.assertEqual(search("ab", "abxab"), [0, 3])

    def test_search_overlap(self):
        self.assertEqual(search("aa", "aaaa"), [0, 1, 2])

    def test_search_empty_pattern(self):
        self.assertEqual(search("", "abc"), [0, 1, 2, 3])

    def test_search_none(self):
        self.assertEqual(search("xyz", "abc"), [])

    def test_search_full_match(self):
        self.assertEqual(search("abc", "abc"), [0])

    def test_random_brute(self):
        import random, string
        for _ in range(200):
            n = random.randint(0, 40)
            alpha = "ab"
            s = "".join(random.choice(alpha) for _ in range(n))
            p = "".join(random.choice(alpha) for _ in range(random.randint(0, 6)))
            # brute
            brute = [i for i in range(len(s) + 1) if s.startswith(p, i)] if p else list(range(len(s) + 1))
            self.assertEqual(search(p, s), brute, (s, p))


if __name__ == "__main__":
    unittest.main()