python接口測試之mock

你知道嗎？ Python3裏自帶的mock非常好用，它可以幫助你擺脫底層某些依賴，將測試的重點聚焦在主邏輯上

本Demo的目錄結構：

Demo
|-- bin
|   | -- __init__.py
|   | -- example.py
|-- tests
|   | -- __init__.py
|   | -- test_example.py

1. 被測接口實現

# -*- coding: utf-8 -*-
"""
@author: TerryJay 
@time: 2020/4/11 17:38
"""

from requests import get


# 底層API：獲取Github的公共時間線
def get_events():
	responses = get('https://api.github.com/events')

	return responses


# 被測函數：判斷id是否爲奇數
def is_old_number(res):
	events_id = res.get("id")
	if int(events_id) % 2:
		return "NO"
	else:
		return "YES"

2. 使用unittest庫的mock.patch替換掉底層API，使被測函數脫離依賴

# -*- coding: utf-8 -*-
"""
@author: TerryJay 
@time: 2020/4/11 17:38
"""

import unittest
from unittest.mock import patch
import bin.example


class Test_set(unittest.TestCase):
	# 自行定義get_events的返回結果，可以看到id是一個偶數，那麼預期結果應該是YES
	fixed_result = {"id": "12021751522", "type": "PullRequestEvent"}

	@patch('bin.example.get', return_value=fixed_result)
	def test_is_old_number(self, mock_get):
		# get_events函數裏使用了get方法，它會被patch替換掉
		time_line = bin.example.get_events()
		result = bin.example.is_old_number(time_line)
		self.assertTrue(mock_get.called)
		self.assertEqual(result, "YES")


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

3. 運行結果

因爲我們定義好的值是id=12021751522，明顯看出是個偶數，那麼我們的預期是is_old_number函數應返回YES

..

----------------------------------------------------------------------
Ran 1 test in 0.000s

OK

如果斷言設置時寫錯了， 將self.assertEqual(result, "YES")改爲self.assertEqual(result, "NO")
再次運行就會拋出異常，這時發現是我們測試人員的預期不正確，注意斷言的預期一定要符合需求。

Failure
Traceback (most recent call last):
  File "I:\Anaconda3\lib\unittest\case.py", line 59, in testPartExecutor
    yield
  File "I:\Anaconda3\lib\unittest\case.py", line 605, in run
    testMethod()
  File "I:\Anaconda3\lib\unittest\mock.py", line 1179, in patched
    return func(*args, **keywargs)
  File "H:\Panda\bin\test_example.py", line 24, in test_is_old_number
    self.assertEqual(result, "NO")
  File "I:\Anaconda3\lib\unittest\case.py", line 829, in assertEqual
    assertion_func(first, second, msg=msg)
  File "I:\Anaconda3\lib\unittest\case.py", line 1202, in assertMultiLineEqual
    self.fail(self._formatMessage(msg, standardMsg))
  File "I:\Anaconda3\lib\unittest\case.py", line 670, in fail
    raise self.failureException(msg)
AssertionError: 'YES' != 'NO'
- YES
+ NO



F

======================================================================
FAIL: test_is_old_number (test_example.Test_set)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "I:\Anaconda3\lib\unittest\mock.py", line 1179, in patched
    return func(*args, **keywargs)
  File "H:\Panda\bin\test_example.py", line 24, in test_is_old_number
    self.assertEqual(result, "NO")
AssertionError: 'YES' != 'NO'
- YES
+ NO


----------------------------------------------------------------------
Ran 1 test in 0.002s

FAILED (failures=1)