def test_reverse_subsequence(self):
result = lcs("xablar", "ralbax")
self.assertIn(result, ("aba", "ala"))
def test_both_strings_are_empty(self):
self.assertEqual(lcs("", ""), "")
def test_subsequences(self):
self.assertEqual(lcs("nahybser", "iunkayxbis"), "naybs")
self.assertEqual(lcs("z1artunx", "yz21rx"), "z1rx")
self.assertEqual(lcs("z1arxzyx1a", "yz21rx"), "z1rx")
self.assertEqual(lcs("yillnum", "numyjiljil"), "yill")
def test_substring_in_the_middle(self):
self.assertEqual(lcs("xyaban", "abarab"), "aba")
def test_substring(self):
self.assertEqual(lcs("abab", "ab"), "ab")
def test_equal_strings(self):
self.assertEqual(lcs("abcd", "abcd"), "abcd")
def test_one_string_is_empty(self):
self.assertEqual(lcs("", "abcd"), "")
self.assertEqual(lcs("abcd", ""), "")