mobius_test.py

# Import the mobius function
import sys
import unittest

# For importing from different folders
# OBS: This is supposed to be done with automated testing, hence relative to folder we want to import from
sys.path.append("Algorithms/math/mobius")

# If run from local:
# sys.path.append('../../Algorithms/math/mobius')

from mobius import mobius


class TestMobius(unittest.TestCase):
    """Test cases for the Mobius function."""
    
    def test_mobius_one(self):
        """Test μ(1) = 1 (special case, zero prime factors)."""
        self.assertEqual(mobius(1), 1)
    
    def test_mobius_prime_two(self):
        """Test μ(2) = -1 (single prime factor)."""
        self.assertEqual(mobius(2), -1)
    
    def test_mobius_prime_three(self):
        """Test μ(3) = -1 (single prime factor)."""
        self.assertEqual(mobius(3), -1)
    
    def test_mobius_prime_large(self):
        """Test μ(17) = -1 (single prime factor - larger prime)."""
        self.assertEqual(mobius(17), -1)
    
    def test_mobius_two_primes(self):
        """Test μ(6) = 1 (two distinct prime factors: 2 × 3)."""
        self.assertEqual(mobius(6), 1)
    
    def test_mobius_two_primes_alternative(self):
        """Test μ(10) = 1 (two distinct prime factors: 2 × 5)."""
        self.assertEqual(mobius(10), 1)
    
    def test_mobius_three_primes(self):
        """Test μ(30) = -1 (three distinct prime factors: 2 × 3 × 5)."""
        self.assertEqual(mobius(30), -1)
    
    def test_mobius_three_primes_alternative(self):
        """Test μ(42) = -1 (three distinct prime factors: 2 × 3 × 7)."""
        self.assertEqual(mobius(42), -1)
    
    def test_mobius_four_primes(self):
        """Test μ(210) = 1 (four distinct prime factors: 2 × 3 × 5 × 7)."""
        self.assertEqual(mobius(210), 1)
    
    def test_mobius_five_primes(self):
        """Test μ(2310) = -1 (five distinct prime factors: 2 × 3 × 5 × 7 × 11)."""
        self.assertEqual(mobius(2310), -1)
    
    def test_mobius_squared_prime_four(self):
        """Test μ(4) = 0 (4 = 2², has squared factor)."""
        self.assertEqual(mobius(4), 0)
    
    def test_mobius_squared_prime_nine(self):
        """Test μ(9) = 0 (9 = 3², has squared factor)."""
        self.assertEqual(mobius(9), 0)
    
    def test_mobius_squared_factor_twelve(self):
        """Test μ(12) = 0 (12 = 2² × 3, has squared factor)."""
        self.assertEqual(mobius(12), 0)
    
    def test_mobius_squared_factor_eighteen(self):
        """Test μ(18) = 0 (18 = 2 × 3², has squared factor)."""
        self.assertEqual(mobius(18), 0)
    
    def test_mobius_squared_factor_large(self):
        """Test μ(72) = 0 (72 = 2³ × 3², has squared factors)."""
        self.assertEqual(mobius(72), 0)
    
    def test_mobius_squared_factor_hundred(self):
        """Test μ(100) = 0 (100 = 2² × 5², has squared factors)."""
        self.assertEqual(mobius(100), 0)
    
    def test_mobius_square_free_fifteen(self):
        """Test μ(15) = 1 (15 = 3 × 5, two distinct primes)."""
        self.assertEqual(mobius(15), 1)
    
    def test_mobius_square_free_thirtyfive(self):
        """Test μ(35) = 1 (35 = 5 × 7, two distinct primes)."""
        self.assertEqual(mobius(35), 1)
    
    def test_mobius_square_free_oneohfive(self):
        """Test μ(105) = -1 (105 = 3 × 5 × 7, three distinct primes)."""
        self.assertEqual(mobius(105), -1)
    
    def test_mobius_invalid_zero(self):
        """Test that μ(0) raises ValueError."""
        with self.assertRaises(ValueError):
            mobius(0)
    
    def test_mobius_invalid_negative(self):
        """Test that μ(-5) raises ValueError."""
        with self.assertRaises(ValueError):
            mobius(-5)
    
    def test_mobius_invalid_float(self):
        """Test that μ(3.5) raises ValueError."""
        with self.assertRaises(ValueError):
            mobius(3.5)
    
    def test_mobius_invalid_string(self):
        """Test that μ('10') raises ValueError."""
        with self.assertRaises(ValueError):
            mobius('10')


if __name__ == "__main__":
    print("Running Mobius function tests:")
    unittest.main()