test_calc.py

import calculator
import unittest


class TestClass(unittest.TestCase):

    def test_add(self):
        """ test for the add function """

        self.assertEqual(calculator.add(10, 15), 25)
        self.assertEqual(calculator.add(10, 25), 35)
        self.assertEqual(calculator.add(20, 11), 31)

    def test_substract(self):
        """ test for the substract function """

        result = calculator.substract(10, 5)
        self.assertEqual(result, 5)

    def test_divide(self):
        """ test for the divide function """
        result = calculator.multiply(10, 2)
        self.assertEqual(result, 20)

    def test_divide_not_by_zero(self):
        """ test for dividing a number by zero, should return a value error """
        self.assertRaises(ValueError, calculator.divide, 10, 0)


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