如何对开放功能进行单元测试和模拟

Question

在过去的 6 个小时里，我读了很多文章，但我仍然不明白嘲笑和单元测试。我想对开放函数进行单元测试，如何正确执行此操作？

我也担心，因为我的大部分代码正在使用外部文件进行数据导入和操作。我知道我需要嘲笑他们进行测试，但我正在努力了解如何前进。

请提供一些建议。提前谢谢你

prototype5.py

import os
import sys
import io
import pandas
pandas.set_option('display.width', None)
def openSetupConfig (a):
"""
SUMMARY
Read setup file
setup file will ONLY hold the file path of the working directory
:param a: str
:return: contents of the file stored as str
"""
try:
setupConfig = open(a, "r")
return setupConfig.read()
except Exception as ve:
ve = (str(ve) + "nnPlease ensure setup file " + str(a) + " is available")
sys.exit(ve)
dirPath = openSetupConfig("Setup.dat")

test_prototype5.py

import prototype5
import unittest
class TEST_openSetupConfig (unittest.TestCase):
"""
Test the openSetupConfig function from the prototype 5 library
"""
def test_open_correct_file(self):
result = prototype5.openSetupConfig("Setup.dat")
self.assertTrue(result)

if __name__ == '__main__':
unittest.main()

Answer 1

因此，经验法则是模拟、存根或伪造所测试方法/函数的所有外部依赖项。关键是孤立地测试逻辑。因此，在您的情况下，您希望测试它是否可以打开文件或在无法打开时记录错误消息。

import unittest
from mock import patch
from prototype5 import openSetupConfig  # you don't want to run the whole file
import __builtin__  # needed to mock open
def test_openSetupConfig_with_valid_file(self):
"""
It should return file contents when passed a valid file.
"""
expect = 'fake_contents'
with patch('__builtin__.open', return_value=expect) as mock_open:
actual = openSetupConfig("Setup.dat")
self.assertEqual(expect, actual)
mock_open.assert_called()
@patch('prototype5.sys.exit')
def test_openSetupConfig_with_invalid_file(self, mock_exit):
"""
It should log an error and exit when passed an invalid file.
"""
with patch('__builtin__.open', side_effect=FileNotFoundError) as mock_open:
openSetupConfig('foo')
mock_exit.assert_called()