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selenium grid for python error

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我在ubuntu virtualbox上为python 3运行selenium grid,我设置了一个网格

java -jar selenium-server-standalone-3.4.0.jar -port 4444 -role hub

一切似乎都好我上了终点站

信息 - Selenium Grid集线器已启动并正在运行

我添加一个节点

java -jar selenium-server-standalone-3.4.0.jar -role webdriver -browser "browserName=firefox,version=54,maxinstance=2,platform=LINUX" -hub http://localhost:4444/grid/register -port 5555

一切似乎都好我上了终点站

信息 - 节点已注册到集线器并可供使用

INFO - SessionCleaner使用insideBrowserTimeout 0初始化,clientGoneTimeout 1800000每180000轮询一次

如果我用节点地址http://10.0.2.15:5555/wd/hub运行此代码一切正常

PLATFORM = 'LINUX' 
BROWSER = 'firefox'

     def setUp(self):
         desired_caps = {}
         desired_caps['platform'] = self.PLATFORM
        desired_caps['browserName'] = self.BROWSER
         self.driver = \
             webdriver.Remote('http://10.0.2.15:5555/wd/hub', desired_caps)
         self.driver.get("https://www.facebook.com/login/")
         self.driver.implicitly_wait(30)    self.driver.maximize_window()

如果我运行上面的代码与网格地址http://10.0.2.15:4444/wd/hub像它应该是我必须总是得到一个错误:

Error
Traceback (most recent call last):
  File "/home/thorbuntu/PycharmProjects/seletests/grid_test.py", line 21, in setUp
    webdriver.Remote('http://10.0.2.15:4444/wd/hub', desired_caps)
  File "/usr/local/lib/python3.5/dist-packages/selenium/webdriver/remote/webdriver.py", line 98, in __init__
    self.start_session(desired_capabilities, browser_profile)
  File "/usr/local/lib/python3.5/dist-packages/selenium/webdriver/remote/webdriver.py", line 188, in start_session
    response = self.execute(Command.NEW_SESSION, parameters)
  File "/usr/local/lib/python3.5/dist-packages/selenium/webdriver/remote/webdriver.py", line 256, in execute
    self.error_handler.check_response(response)
  File "/usr/local/lib/python3.5/dist-packages/selenium/webdriver/remote/errorhandler.py", line 194, in check_response
    raise exception_class(message, screen, stacktrace)
selenium.common.exceptions.WebDriverException: Message: None
Stacktrace:
    at java.util.HashMap.putMapEntries (HashMap.java:500)
    at java.util.HashMap.putAll (HashMap.java:784)
    at org.openqa.selenium.remote.DesiredCapabilities.<init> (DesiredCapabilities.java:55)
    at org.openqa.grid.web.servlet.handler.RequestHandler.process (RequestHandler.java:104)
    at org.openqa.grid.web.servlet.DriverServlet.process (DriverServlet.java:83)
    at org.openqa.grid.web.servlet.DriverServlet.doPost (DriverServlet.java:67)
    at javax.servlet.http.HttpServlet.service (HttpServlet.java:707)
    at javax.servlet.http.HttpServlet.service (HttpServlet.java:790)
    at org.seleniumhq.jetty9.servlet.ServletHolder.handle (ServletHolder.java:841)
    at org.seleniumhq.jetty9.servlet.ServletHandler.doHandle (ServletHandler.java:543)
    at org.seleniumhq.jetty9.server.handler.ScopedHandler.nextHandle (ScopedHandler.java:188)
    at org.seleniumhq.jetty9.server.session.SessionHandler.doHandle (SessionHandler.java:1584)
    at org.seleniumhq.jetty9.server.handler.ScopedHandler.nextHandle (ScopedHandler.java:188)
    at org.seleniumhq.jetty9.server.handler.ContextHandler.doHandle (ContextHandler.java:1228)
    at org.seleniumhq.jetty9.server.handler.ScopedHandler.nextScope (ScopedHandler.java:168)
    at org.seleniumhq.jetty9.servlet.ServletHandler.doScope (ServletHandler.java:481)
    at org.seleniumhq.jetty9.server.session.SessionHandler.doScope (SessionHandler.java:1553)
    at org.seleniumhq.jetty9.server.handler.ScopedHandler.nextScope (ScopedHandler.java:166)
    at org.seleniumhq.jetty9.server.handler.ContextHandler.doScope (ContextHandler.java:1130)
    at org.seleniumhq.jetty9.server.handler.ScopedHandler.handle (ScopedHandler.java:141)
    at org.seleniumhq.jetty9.server.handler.HandlerWrapper.handle (HandlerWrapper.java:132)
    at org.seleniumhq.jetty9.server.Server.handle (Server.java:564)
    at org.seleniumhq.jetty9.server.HttpChannel.handle (HttpChannel.java:320)
    at org.seleniumhq.jetty9.server.HttpConnection.onFillable (HttpConnection.java:251)
    at org.seleniumhq.jetty9.io.AbstractConnection$ReadCallback.succeeded (AbstractConnection.java:279)
    at org.seleniumhq.jetty9.io.FillInterest.fillable (FillInterest.java:112)
    at org.seleniumhq.jetty9.io.ChannelEndPoint$2.run (ChannelEndPoint.java:124)
    at org.seleniumhq.jetty9.util.thread.QueuedThreadPool.runJob (QueuedThreadPool.java:672)
    at org.seleniumhq.jetty9.util.thread.QueuedThreadPool$2.run (QueuedThreadPool.java:590)
    at java.lang.Thread.run (Thread.java:748)

哪里可能是我在virtualbox和selenium python上运行ubuntu的问题

非常感谢

1 回答

  • 1

    你可能实际上遇到了网格方面的一个错误(已经修复但尚未发布)

    当你的python客户端代码通过以下行实例化一个新的远程WebDriver时

    desired_caps = {}
    desired_caps['platform'] = self.PLATFORM
    desired_caps['browserName'] = self.BROWSER
    
    self.driver = webdriver.Remote('http://10.0.2.15:4444/wd/hub', desired_caps)
    

    这将转换为以下形式的JSON有效内容

    {
        "capabilities": {
            "alwaysMatch": {
                "browserName": "chrome"
            },
            "firstMatch": [
    
            ]
        },
        "desiredCapabilities": {
            "browserName": "chrome"
        }
    }
    

    在网格方面(Selenium Grid v.3.4.0),集线器尝试使用 org.openqa.grid.web.servlet.handler.WebDriverRequest#extractDesiredCapability 中的以下逻辑将此JSON解析为所需的功能:

    public Map<String, Object> extractDesiredCapability() {
        String json = getBody();
        try {
          JsonObject map = new JsonParser().parse(json).getAsJsonObject();
          // Current W3C has required / desired capabilities wrapped in a 'capabilites' object.
          // This will need to be updated if/when https://github.com/w3c/webdriver/pull/327 gets merged
          if (map.has("capabilities")) {
            return new JsonToBeanConverter().convert(Map.class, map.getAsJsonObject("capabilities").getAsJsonObject("desiredCapabilities"));
          }
          JsonObject dc = map.get("desiredCapabilities").getAsJsonObject();
          return new JsonToBeanConverter().convert(Map.class, dc);
    
        } catch (Exception e) {
          throw new GridException("Cannot extract a capabilities from the request: " + json, e);
        }
    }
    

    如您所见,此逻辑最终返回所需功能的NULL值,因为:

    • 在JSON Payload中,找到了元素 capabilities 但是在JSON子元素 capabilities 内,没有名为 desiredCapabilities 的子元素

    • 这会导致通过 extractDesiredCapability() 返回NULL映射,并最终触发 NullPointerException .

    我知道现在已经在Selenium Grid代码库中修复了这个问题,作为this commit的一部分,它在实例化HashMap之前添加了Null Check防护,并且this commit确保Grid基本上检查是否:

    • JSON有效负载有一个名为 capabilities 的密钥

    • capabilities 键中有一个名为 desiredCapabilities 的子项,它在尝试将这些功能提取为 Map 之前,如果不是只查找键 desiredCapabilities .

    另一方面,如果您将测试代码直接指向节点,则它可以正常工作,因为当测试路由到节点时,不会涉及上述解析 .

    所以现在我建议你回滚使用Selenium 2.53.1 of Grid,直到下一个版本(包含上面提到的两个提交)发布 .

    希望有所帮助 .

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