Selenium Python教程第6章：使用页面对象

6. Page Objects 页面对象

6.1 什么是页面对象模型(POM)？

页面对象模型(Page Objects Model, POM )是一组旨在表示一个或多个网页的类, 用1个类来保存1个网页上所有的元素，相似的网页可以重用此类。
1个网站通常有多个页面，可以用多个页面类对象分别代表各个页面，其好处有：

• web应用测试程序或者爬虫程序的结构更加清晰易懂。
• 对于结构相似的多个网页，可减少重复的代码量
• 如果web页面元素发生变化，只需要修改一处

6.2 使用页面对象的项目结构

使用页面对象的项目的通常结构类似于

 |-- pages
    |--- locators.py
    |--- elements.py
    |--- pages.py
|-- tests
    |--- test_contact_page.py

各文件说明：

• pages.py 定义页面元素，以及针对各元素的操作方法
• locators.py 分离定位字符。通常做法，同一页面的定位器属于同一个类
• elements.py 通常定义1个页面元素的基类，提供set(), get()方法
• test_*.py 测试用例类test case class文件

6.2 源码文件及说明

6.2.1 测试用例类源码

本例 test_contact_page.py 用于在colibri-software.com网站填写 Contact Me表单，判断是否填写结果是否成功

import unittest
from selenium import webdriver
import pages

class TestColibriSoftwareContactMe(unittest.TestCase):

    def setUp(self):
        self.driver = webdriver.Firefox()
        self.driver.get("https://www.colibri-software.com")

    def test_submit_contact_me_form(self):
        """
         "Contact me" 测试表单
        填写各字段，提交表单，验证提交是否成功
        """

        # 加载主页，本例为 colibri-software.com主页
        contact_page = pages.ContactPage(self.driver)

        # Checks if the word "Contact" is in title
        assert contact_page.is_title_matches()

        # 向表单各字段填写内容
        contact_page.name_input = 'John Doe'
        contact_page.company_name_input = 'John Doe\'s paper company'
        contact_page.email_input = '[email protected]'
        contact_page.additional_info_input = 'I need a website to sell paper online'

        # 提前表单
        contact_page.click_submit_form_button()

        # 验结果是否成功
        assert contact_page.success_message_is_displayed()

    def tearDown(self):
        self.driver.close()

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

6.2.2 页面对象类源码

pages.py 介绍如何编写页面对象类

from elements import BasePageElement
from locators import ContactPageLocators

class NameElement(BasePageElement):
    """
    This class gets the search text from the specified locator
    """

    # The locator for text box where name is entered
    locator = 'wpforms-236-field_0'

# Similar classes for other text fields    
class CompanyNameElement(BasePageElement):

    locator = 'wpforms-236-field_4'

class EmailElement(BasePageElement):

    locator = 'wpforms-236-field_1'

class AdditionalInfoElement(BasePageElement):

    locator = 'wpforms-236-field_0'

class BasePage(object):
    """
    Base class to initialize the base page that will be called from all pages
    """

    def __init__(self, driver):
        self.driver = driver

class ContactPage(BasePage):
    """
    Contact page action methods come here
    """

    # Declares text input fields
    name_input = NameElement()
    company_name_input = CompanyNameElement()
    email_input = EmailElement()
    additional_info_input = AdditionalInfoElement()

    def is_title_matches(self):
        """
        Verifies that the text "Contact" appears in page title
        """
        return 'Contact' in self.driver.title

    def click_submit_form_button(self):
        """
        Submits the form
        """
        element = self.driver.find_element(*ContactPageLocators.SUBMIT_FORM_BUTTON)
        element.click()

    def success_message_is_displayed(self):
        success_message = 'Thanks for contacting us! We will be in touch with you shortly.'
        return success_message in self.driver.page_source

6.2.3 页面元素基类源码

elements.py 定义1个页面元素的基类，提供set(), get()方法

from selenium.webdriver.support.ui import WebDriverWait

class BasePageElement(object):
    """
    Base page class that is initialized on every page object class.
    """

    def __set__(self, obj, value):
        """
        Sets the text to the value supplied
        """
        driver = obj.driver
        WebDriverWait(driver, 100).until(lambda driver: driver.find_element_by_id(self.locator))
        driver.find_element_by_id(self.locator).clear()
        driver.find_element_by_id(self.locator).send_keys(value)

    def __get__(self, obj, owner):
        """
        Gets the text of the specified object
        """
        driver = obj.driver
        WebDriverWait(driver, 100).until(lambda driver: driver.find_element_by_id(self.locator))
        element = driver.find_element_by_id(self.locator)
        return element.get_attribute("value")

6.2.4 locators 定位器类
一个好的编程习惯做法是，分离定位字符。在这个例子中，同一页面的定位器属于同一个类。

from selenium.webdriver.common.by import By

class ContactPageLocators(object):
    """
    A class for all Contact page locators.
    """
    SUBMIT_FORM_BUTTON = (By.CSS_SELECTOR, 'button[type="submit"]')

class SearchResultsPageLocators(object):
    """A class for search results locators. All search results locators should come here"""
    pass