test_main.py

import unittest
from main import Calculator


class TestCalculator(unittest.TestCase):

    def setUp(self):
        self.calc = Calculator()

    def test_add(self):
        self.assertEqual(self.calc.add(2, 3), 5)
        self.assertEqual(self.calc.add(-1, 1), 0)

    def test_subtract(self):
        self.assertEqual(self.calc.subtract(10, 4), 6)
        self.assertEqual(self.calc.subtract(0, 5), -5)

    def test_multiply(self):
        self.assertEqual(self.calc.multiply(3, 4), 12)
        self.assertEqual(self.calc.multiply(0, 100), 0)

    def test_divide(self):
        self.assertEqual(self.calc.divide(10, 2), 5.0)
        self.assertEqual(self.calc.divide(9, 3), 3.0)

    def test_divide_by_zero(self):
        with self.assertRaises(ValueError):
            self.calc.divide(5, 0)


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