Calculator test functions

calculator_test.py

import unittest
from calculator import Calculator

# test the calculator functionality
class TestCalculator(unittest.TestCase):
    def setUp(self):
        self.calc = Calculator()

    # this tests the add functionality
    # 2 + 2 = 4
    # 2 + 4 = 6
    # 2 + (-2) = 0

    def test_calculator_add_method_returns_correct_result(self):
        result = self.calc.add(2, 2)
        self.assertEqual(4, result)
        result = self.calc.add(2, 4)
        self.assertEqual(6, result)
        result = self.calc.add(2, -2)
        self.assertEqual(0, result)
		
	# this tests the subtract functionality
	# 2 - 2 = 0
	# 2 - 4 = -2
	# 2 - (-4) = 6

    def test_calculator_subtract_method_returns_correct_result(self):
        result = self.calc.subtract(2, 2)
        self.assertEqual(0, result)
        result = self.calc.subtract(2, 4)
        self.assertEqual(-2, result)
        result = self.calc.subtract(2, -4)
        self.assertEqual(6, result)