前言

我们每一个的selenium测试都应该在指定的环境下运行，这个环境可以是web浏览器、移动设备、移动模拟器等等。

那怎么来指定我们的selenium测试脚本运行环境呢？

本次分享主要解决这个问题！！！

在python版本的webdrive中，DesiredCapabilities类为我们提供了解决方案，通过这个类，我们能够配置webdriver在指定的环境执行我们的测试脚本。

我们先看一张实际测试过程中会应用到的结构图，基于selenium grid进行分布式测试：

selenium_grid.png

在上图中，我们可以使用windows下ie、firefox或linux下ie、firefox进行测试，甚至可以设置使用andriod或ios设备下浏览器进行测试。

那怎么来进行设置呢？

我们先看一下DesiredCapabilities的源码

源码分析

DesiredCapabilities类代码在C:\Python27\Lib\site-packages\selenium\webdriver\common\desired_capabilities.py。

注：笔者的python安装在C盘下。

class DesiredCapabilities(object):
    """
    Set of default supported desired capabilities.

    Use this as a starting point for creating a desired capabilities object for
    requesting remote webdrivers for connecting to selenium server or selenium grid.

    Usage Example::

        from selenium import webdriver

        selenium_grid_url = "http://198.0.0.1:4444/wd/hub"

        # Create a desired capabilities object as a starting point.
        capabilities = DesiredCapabilities.FIREFOX.copy()
        capabilities['platform'] = "WINDOWS"
        capabilities['version'] = "10"

        # Instantiate an instance of Remote WebDriver with the desired capabilities.
        driver = webdriver.Remote(desired_capabilities=capabilities,
                                  command_executor=selenium_grid_url)

    Note: Always use '.copy()' on the DesiredCapabilities object to avoid the side
    effects of altering the Global class instance.

    """

    FIREFOX = {
        "browserName": "firefox",
        "version": "",
        "platform": "ANY",
        "javascriptEnabled": True,
        "marionette": True,
    }

    INTERNETEXPLORER = {
        "browserName": "internet explorer",
        "version": "",
        "platform": "WINDOWS",
        "javascriptEnabled": True,
    }

    EDGE = {
        "browserName": "MicrosoftEdge",
        "version": "",
        "platform": "WINDOWS"
    }

    CHROME = {
        "browserName": "chrome",
        "version": "",
        "platform": "ANY",
        "javascriptEnabled": True,
    }

    OPERA = {
        "browserName": "opera",
        "version": "",
        "platform": "ANY",
        "javascriptEnabled": True,
    }

    SAFARI = {
        "browserName": "safari",
        "version": "",
        "platform": "MAC",
        "javascriptEnabled": True,
    }

    HTMLUNIT = {
        "browserName": "htmlunit",
        "version": "",
        "platform": "ANY",
    }

    HTMLUNITWITHJS = {
        "browserName": "htmlunit",
        "version": "firefox",
        "platform": "ANY",
        "javascriptEnabled": True,
    }

    IPHONE = {
        "browserName": "iPhone",
        "version": "",
        "platform": "MAC",
        "javascriptEnabled": True,
    }

    IPAD = {
        "browserName": "iPad",
        "version": "",
        "platform": "MAC",
        "javascriptEnabled": True,
    }

    ANDROID = {
        "browserName": "android",
        "version": "",
        "platform": "ANDROID",
        "javascriptEnabled": True,
    }

    PHANTOMJS = {
        "browserName": "phantomjs",
        "version": "",
        "platform": "ANY",
        "javascriptEnabled": True,
    }

翻译下：

Set of default supported desired capabilities.
desired capabilities默认支持的设置。

Use this as a starting point for creating a desired capabilities object for
requesting remote webdrivers for connecting to selenium server or selenium grid.
使用该类为selenium server或selenium grid启动一个desired capabilities配置

对配置项进行解释

FIREFOX = {
    "browserName": "firefox",  # 浏览器名称
    "version": "",             # 操作系统版本
    "platform": "ANY",         # 平台，这里可以是windows、linux、andriod等等
    "javascriptEnabled": True, # 是否启用js
    "marionette": True,        # 这个值没找对应的说明^_^  不解释了
}

DesiredCapabilities示例

from selenium import webdriver

# 本地启动selenium grid
selenium_grid_url = "http://127.0.0.1:4444/wd/hub"

# 创建一个DesiredCapabilities实例
capabilities = DesiredCapabilities.FIREFOX.copy()
capabilities['platform'] = "WINDOWS"  # 指定操作系统
capabilities['version'] = "10"   # 指定操作系统版本

# 连接到远程服务进行自动化测试
driver = webdriver.Remote(desired_capabilities=capabilities,
                          command_executor=selenium_grid_url)

总结

这里的本质就是基于selenium grid 构建分布式自动化测试，而selenium grid根据测试脚本构建的DesiredCapabilities参数来决定将您的测试脚本分发到哪台机器或设备进行测试。