Python 面试：单元测试unit testing 使用pytest

1. 对于函数进行单元测试

calc.py

def add(x, y):"""Add Function"""return x + ydef subtract(x, y):"""Subtract Function"""return x - ydef multiply(x, y):"""Multiply Function"""return x * ydef divide(x, y):"""Divide Function"""if y == 0: raise ValueError('Can not divide by zero!')return x / y

test_calc.py

import unittest
import calcclass TestCalc(unittest.TestCase):def test_add(self):self.assertEqual(calc.add(10, 5), 15)self.assertEqual(calc.add(-1, 1), 0)self.assertEqual(calc.add(-1, -1), -2)def test_subtract(self):self.assertEqual(calc.subtract(10, 5), 5)self.assertEqual(calc.subtract(-1, 1), -2)self.assertEqual(calc.subtract(-1, -1), 0)def test_multiply(self):self.assertEqual(calc.multiply(10, 5), 50)self.assertEqual(calc.multiply(-1, 1), -1)self.assertEqual(calc.multiply(-1, -1), 1)def test_divide(self):self.assertEqual(calc.divide(10, 5), 2)self.assertEqual(calc.divide(-1, 1), -1)self.assertEqual(calc.divide(-1, -1), 1)self.assertRaises(ValueError, calc.divide, 10, 0)if __name__ == '__main__':unittest.main()

2. 对于对象(object)进行单元测试

employee.py

class Employee:"""A sample Employee class"""raise_amt = 1.05def __init__(self, first, last, pay):self.first = firstself.last = lastself.pay = pay@propertydef email(self):return '{}.{}@email.com'.format(self.first, self.last)@propertydef fullname(self):return '{} {}'.format(self.first, self.last)def apply_raise(self):self.pay = int(self.pay * self.raise_amt)

test_employee.py

import unittest
from employee import Employeeclass TestEmployee(unittest.TestCase):@classmethoddef setUpClass(cls):print('setupClass')@classmethoddef tearDownClass(cls):print('teardownClass')def setUp(self):print('setUp')self.emp_1 = Employee('Elon', 'Musk', 50000)self.emp_2 = Employee('Sue', 'Smith', 60000)def tearDown(self):print('tearDown\n')def test_email(self):print('test_email')self.assertEqual(self.emp_1.email, '[e-mail]')self.assertEqual(self.emp_2.email, '[e-mail]')self.emp_1.first = 'John'self.emp_2.first = 'Jane'self.assertEqual(self.emp_1.email, '[e-mail]')self.assertEqual(self.emp_2.email, '[e-mail]')def test_fullname(self):print('test_fullname')self.assertEqual(self.emp_1.fullname, 'Elon Musk')self.assertEqual(self.emp_2.fullname, 'Sue Smith')self.emp_1.first = 'John'self.emp_2.first = 'Jane'self.assertEqual(self.emp_1.fullname, 'John Musk')self.assertEqual(self.emp_2.fullname, 'Jane Smith')def test_apply_raise(self):print('test_apply_raise')self.emp_1.apply_raise()self.emp_2.apply_raise()self.assertEqual(self.emp_1.pay, 52500)self.assertEqual(self.emp_2.pay, 63000)if __name__ == '__main__':unittest.main()

输出为：
setupClass
setUp
test_apply_raise
tearDown

.setUp
test_email
tearDown

.setUp
test_fullname
tearDown

.teardownClass

---

Ran 3 tests in 0.001s

OK

3. 使用mock模拟对象库

employee.py

import requestsclass Employee:"""A sample Employee class"""raise_amt = 1.05def __init__(self, first, last, pay):self.first = firstself.last = lastself.pay = pay@propertydef email(self):return '{}.{}@email.com'.format(self.first, self.last)@propertydef fullname(self):return '{} {}'.format(self.first, self.last)def apply_raise(self):self.pay = int(self.pay * self.raise_amt)def monthly_schedule(self, month):response = requests.get(f'http://company.com/{self.last}/{month}')if response.ok:return response.textelse:return 'Bad Response!'

test_employee.py

import unittest
from unittest.mock import patch
from employee import Employeeclass TestEmployee(unittest.TestCase):@classmethoddef setUpClass(cls):print('setupClass')@classmethoddef tearDownClass(cls):print('teardownClass')def setUp(self):print('setUp')self.emp_1 = Employee('Elon', 'Musk', 50000)self.emp_2 = Employee('Sue', 'Smith', 60000)def tearDown(self):print('tearDown\n')# Test 1def test_email(self):print('test_email')self.assertEqual(self.emp_1.email, '[e-mail]')self.assertEqual(self.emp_2.email, '[e-mail]')self.emp_1.first = 'John'self.emp_2.first = 'Jane'self.assertEqual(self.emp_1.email, '[e-mail]')self.assertEqual(self.emp_2.email, '[e-mail]')# Test 2def test_fullname(self):print('test_fullname')self.assertEqual(self.emp_1.fullname, 'Elon Musk')self.assertEqual(self.emp_2.fullname, 'Sue Smith')self.emp_1.first = 'John'self.emp_2.first = 'Jane'self.assertEqual(self.emp_1.fullname, 'John Musk')self.assertEqual(self.emp_2.fullname, 'Jane Smith')# Test 3def test_apply_raise(self):print('test_apply_raise')self.emp_1.apply_raise()self.emp_2.apply_raise()self.assertEqual(self.emp_1.pay, 52500)self.assertEqual(self.emp_2.pay, 63000)# Test 4def test_monthly_schedule(self):# 模拟替换网络请求with patch('employee.requests.get') as mocked_get:mocked_get.return_value.ok = Truemocked_get.return_value.text = 'Success'schedule = self.emp_1.monthly_schedule('May')mocked_get.assert_called_with('http://company.com/Musk/May')self.assertEqual(schedule, 'Success')mocked_get.return_value.ok = Falseschedule = self.emp_2.monthly_schedule('June')mocked_get.assert_called_with('http://company.com/Smith/June')self.assertEqual(schedule, 'Bad Response!')if __name__ == '__main__':unittest.main()

输出为：
setupClass
setUp
test_apply_raise
tearDown

.setUp
test_email
tearDown

.setUp
test_fullname
tearDown

.setUp
tearDown

.teardownClass

---

Ran 4 tests in 0.001s

OK

4. 使用pytest进行测试

binarysearch.py，主要使用assert。

def binary_search(array, target):if not array:return -1begin, end = 0, len(array)while begin < end:mid = begin + (end - begin) // 2if array[mid] == target:return midelif array[mid] > target:end = midelse:begin = mid + 1return -1def test():assert binary_search([0, 1, 2, 3, 4, 5], 1) == 1assert binary_search([0, 1, 2, 3, 4, 5], 6) == -1assert binary_search([0, 1, 2, 3, 4, 5], -1) == -1assert binary_search([0, 1, 2, 3, 4, 5], 0) == 0assert binary_search([0, 1, 2, 3, 4, 5], 5) == 5assert binary_search([0], 0) == 0assert binary_search([], 1) == -1

在CMD中输入指令：pytest binarysearch.py

输出为：
================================================= test session starts =================================================
platform win32 – Python 3.10.9, pytest-7.1.2, pluggy-1.0.0
rootdir: C:\Users\h13je\Working_Log\01092023\python_learning
plugins: anyio-3.5.0
collected 1 item

binarysearch.py . [100%]

================================================== 1 passed in 0.02s ==================================================