import unittest
from majority_element import majority

class TestMajority(unittest.TestCase):
    def test_basic(self):
        self.assertEqual(majority([1,1,2]), 1)
        self.assertEqual(majority([2,2,1,1,1]), 1)
        self.assertIsNone(majority([1,2,3]))
        self.assertIsNone(majority([]))
        self.assertEqual(majority([5]), 5)
        self.assertEqual(majority([1,1,1,2,2,2,2]), 2)

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