python的unittest框架中如何删除测试数据，清理环境，可以通过addCleanup函数

 def addCleanup(self, function, *args, **kwargs):
        """Add a function, with arguments, to be called when the test is
        completed. Functions added are called on a LIFO basis and are
        called after tearDown on test failure or success.

        Cleanup items are called even if setUp fails (unlike tearDown)."""
        self._cleanups.append((function, args, kwargs))

添加针对每个测试用例执行完tearDown()方法之后的清理方法，添加进去的函数按照LIFO的顺序，通过参数添加进去

如果setUp()执行失败，就不会执行tearDown()，自然也不会执行addCleanup()里添加的函数。

使用场景：正常的测试用例，创建资源后，需要清理环境再在用例中删除资源，或者tearDown()后进行资源清理，不方便，如果用了addCleanup()后，直接在用例中写入函数，在tearDown()用例后，会再次调用addCleanup来删除资源，减少代码量以及遗漏删除。

# _*_ encoding:utf-8 _*_

from selenium import webdriver
from selenium.webdriver.common.by import By
import unittest
import time

class Baidu(unittest.TestCase):

    def abc(self,a):
        print(a)

    def setUp(self):
        self.driver = webdriver.Firefox()
        self.driver.implicitly_wait(10)
        self.base_url = 'http://www.baidu.com'
        print ("This is setUp")

    def test_baidu_search(self):
        driver = self.driver
        driver.get(self.base_url)
        driver.find_element_by_id("kw").send_keys("HTMLTestRunner")
        driver.find_element_by_id("su").click()
        cleanups = ('abcdefg',)
        self.addCleanup(self.abc,
                        cleanups[0])

    def tearDown(self):
        self.driver.quit()
        print ("This is tearDown")

if __name__ == '__main__':
    unittest.main()
    # testsuit = unittest.TestSuite()
    # testsuit.addTest(Baidu("test_baidu_search"))

执行结果如下，可以看到会在用例结束之后，执行addCleanup里的函数，因此可以用来进行，测试环境数据清理工作。

This is setUp
.
----------------------------------------------------------------------
Ran 1 test in 16.072s

OK
This is tearDown
abcdefg