Question

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

一切似乎都没问题我上了终端

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＆＃34; browserName = firefox，version = 54，maxinstance = 2，platform = LINUX＆＃34; -hub http://localhost:4444/grid/register -port 5555

一切似乎都没问题我上了终端

INFO - 节点已注册到集线器并准备使用

INFO - 使用insideBrowserTimeout 0和clientGoneTimeout 1800000每180000轮询初始化SessionCleaner

如果我使用节点地址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()

如果我使用网格地址http://10.0.2.15:4444/wd/hub运行上面的代码，我认为它必须是我总是会收到错误：

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)

我可以在虚拟机和selenium python上运行ubuntu的问题

非常感谢

Answer 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)

这会转换为以下形式的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中，没有名为desiredCapabilities
这会导致通过extractDesiredCapability()返回NULL地图，最终触发NullPointerException。

我知道这已经在Selenium Grid代码库中作为this提交的一部分进行了修复，它在实例化HashMap之前添加了Null Check防护，并且this提交确保Grid基本上检查是否：

JSON有效负载有一个名为capabilities和
在密钥capabilities中，有一个名为desiredCapabilities的子项，在尝试将这些功能提取为地图之前，如果不只是查找密钥desiredCapabilities。

另一方面，如果您将测试代码直接指向节点，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网格的Selenium 2.53.1，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。

selenium grid for python error

1 个答案: