1、基本用法：用于检查代码的运行结果是否正确
    注意：方法必须用test开头

    1. def calc(express):
    2.     try:
    3.         ret=eval(express)
    4.     except:
    5.         return
    6.     else:
    7.         return ret
    8. import unittest
    9. class Test_calc(unittest.TestCase):
    10.     def test_add(self):
    11.         express="1+1"
    12.         ret=calc(express)
    13.         self.assertEqual(2,ret,"%s测试不通过"%express)
    14.     def test_sub(self):
    15.         express="1-1"
    16.         ret=calc(express)
    17.         self.assertEqual(0,ret,"%s测试不通过"%express)
    18.     def test_multi(self):
    19.         express="1*3"
    20.         ret=calc(express)
    21.         self.assertEqual(2,ret,"%s测试不通过"%express)
    22.     def test_divi(self):
    23.         express="1/1"
    24.         ret=calc(express)
    25.         self.assertEqual(1,ret,"%s测试不通过"%express)
    26.     def test_type(self):
    27.         express = "1+1"
    28.         ret = calc(express)
    29.         self.assertIsInstance(ret,str,"类型不一致")
    31. if __name__ == '__main__':
    32.     unittest.main()

    结果：
    image.png