把登录和退出功能单独写到一个公共.py脚本，其它用例test1，test2调用公共登录，退出函数

公共登录/退出函数模块(login_exit.py):

#coding:utf-8
import time
def login(driver, username, password):#此处的driver是个形参,如果不在此处定义就不可以使用

    driver.find_element_by_link_text("登录").click()
    #输入用户名
    driver.find_element_by_css_selector("#input1").send_keys(username)
    time.sleep(2)
    #输入密码
    driver.find_element_by_css_selector("#input2").send_keys(password)
    # 点击登录
    time.sleep(2)
    driver.find_element_by_id("signin").click()

def exit(driver):
    time.sleep(2)
    driver.find_element_by_link_text("退出").click()
    time.sleep(2)
    t = driver.switch_to.alert
    time.sleep(2)
    #print(t.text)
    t.accept()
    time.sleep(2)

用例模块(test.py):

#coding:utf-8
from selenium import webdriver
import unittest,time
from l_and_q import login_exit
class Test_Log(unittest.TestCase):

'''测试类,是多个测试用例的集合,可以把一些相同的操作写成一个类,test_suit'''

    def setUp(self):
        url="https://www.cnblogs.com/"
        self.option = webdriver.ChromeOptions()
        self.option.add_argument('lang=zh_CN.UTF-8')
        self.option.add_argument('User-Agent:"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.90 Safari/537.36"')
        self.driver = webdriver.Chrome(chrome_options=self.option)
        self.driver.get(url)
    def test_1log(self):    #登录失败
        #调用login函数,并向它传参
        login_exit.login(driver=self.driver, username=u"uname", password=u"flasepwd")
        time.sleep(2)
        #实际结果
        actual_result=self.driver.find_element_by_css_selector("#tip_btn").text
        print("实际结果为:"+actual_result)
        time.sleep(2)
        #预期结果
        expected_result = u"用户名或密码错误\n\n联系 contact@cnblogs.com"
        print("预期结果为:" + expected_result)
        time.sleep(2)
        self.assertEqual(actual_result,expected_result,msg="实际结果(%s)与预期结果(%s)不一致"%(actual_result,expected_result))

    def test_2log(self):    #登录成功
        #调用login函数,并向它传参
        login_exit.login(driver=self.driver, username=u"uname", password=u"truepwd")

        time.sleep(2)
        #实际结果
        actual_result=self.driver.find_element_by_css_selector("#span_userinfo>a:nth-child(1)").text
        print("\n实际结果为:"+actual_result)
        #预期结果
        expected_result="女林"
        print("预期结果为:"+expected_result)
        self.assertEqual(actual_result,expected_result,msg="实际结果(%s)与预期结果(%s)不一致"%(actual_result,expected_result))
        time.sleep(2)
        #调用login_exit模块中的exit函数
        login_exit.exit(driver=self.driver)
        time.sleep(2)
    # def test_3log(self):    #退出账号成功
    #     login_exit.login(driver=self.driver, username=u"uname", password=u"truepwd")

    #     login_exit.exit(driver=self.driver)
    #     time.sleep(2)
    #     #实际结果
    #     actual_result=self.driver.find_element_by_css_selector("#span_userinfo>a:nth-child(1)").text
    #     print("\n实际结果为:"+actual_result)
    #     self.assertTrue(actual_result)
    #     # #预期结果
    #     # expected_result="登"
    #     # print("预期结果为:"+expected_result)
    #     # self.assertIn(expected_result,actual_result,msg="实际结果(%s)与预期结果(%s)不一致"%(expected_result,actual_result))
    #     time.sleep(2)
    def tearDown(self):
        self.driver.quit()

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