text: import unittest
  from sexta_of_python.example_classes import Calculator
  
  
  class TestCalculator(unittest.TestCase):
      def add_test(self):
          # Test won't run because it's name does not begins with test_
          self.assertEqual(Calculator.add(20, 5), 50)
  
      def test_add(self):
          self.assertEqual(Calculator.add(20, 5), 25)
          # self.assertEqual(Calculator.add(-5, 5), 1)
          self.assertEqual(Calculator.add(-5, 5), 0)
  
      def test_subtraction(self):
          self.assertEqual(Calculator.subtraction(20, 5), 15)
  
      def test_multiply(self):
          self.assertEqual(Calculator.multiply(20, 5), 100)
  
      def test_divide(self):
          self.assertEqual(Calculator.divide(20, 5), 4)
          # self.assertRaises(ValueError, Calculator.divide, 5, 0)
          self.assertRaises(ValueError, Calculator.divide, 5, 1)
  
      def test_power(self):
          calc = Calculator()
          self.assertEqual(calc.power(2, 5), 32)
  
  
  if __name__ == '__main__':
      unittest.main()
  