4 单元测试，结对

import unittest

from f4_1 import createOperator

class testCreateOperator(unittest.TestCase):
    def test_CreateOperator(self):
        print("单元测试开始：")
        operator = ["+", "-", "*", "/"]
        self.assertIn(createOperator(self),operator)
if __name__ == ‘__main__‘:
    unittest.main()

import unittest

from f4_1 import main

class testmain(unittest.TestCase):
    def test_main(self):
        print("单元测试开始：")

        self.assertIn(main(),20)
if __name__ == ‘__main__‘:
    unittest.main()