问题描述
我使用Selenium 2来测试使用InternetExplorerDriver一个asp.net web窗体页和我遇到一个StaleElementReferenceException。该页面包含一个（自动回传）下拉列表中，其中我从选择不同的值
I am using Selenium 2 to test an asp.net web forms page using the InternetExplorerDriver and am encountering a StaleElementReferenceException. The page contains a (auto-postback) drop down list, which I am selecting different values from.
示例代码：
页：
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication.WebForm1" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:DropDownList ID="ddl" runat="server" AutoPostBack="true">
<asp:ListItem Text="one"></asp:ListItem>
<asp:ListItem Text="two"></asp:ListItem>
</asp:DropDownList>
</div>
</form>
</body>
</html>
（代码隐藏文件中包含什么比在Visual Studio自动创建的东西更多。）
(The code-behind file contains nothing more than the Visual Studio auto-created stuff.)
测试夹具代码：
using NUnit.Framework;
using OpenQA.Selenium;
using OpenQA.Selenium.IE;
namespace IntegrationTests
{
[TestFixture]
public class WebForm1TestFixture
{
[Test]
public void ShouldSelectItemOneThenItemTwo()
{
IWebDriver driver = new InternetExplorerDriver(); // Using ChromeDriver causes test to pass...
driver.Navigate().GoToUrl("http://localhost/<my-virtual-directory-name>/WebForm1.aspx");
IWebElement list = driver.FindElement(By.Id("ddl"));
IWebElement itemOne = list.FindElement(By.XPath("option[1]"));
itemOne.Select();
list = driver.FindElement(By.Id("ddl"));
IWebElement itemTwo = list.FindElement(By.XPath("option[2]"));
itemTwo.Select();
list = driver.FindElement(By.Id("ddl"));
itemOne = list.FindElement(By.XPath("option[1]"));// This line causes the StaleElementReferenceException to occur
itemOne.Select();
// Some assertion would go here
}
}
}
当我运行测试，我得到以下错误：
When I run the test I get the following error:
OpenQA.Selenium.StaleElementReferenceException: Element is no longer valid
at OpenQA.Selenium.Remote.RemoteWebDriver.UnpackAndThrowOnError(Response errorResponse) in e:\Projects\WebDriver\trunk\remote\client\src\csharp\webdriver-remote-client\RemoteWebDriver.cs: line 883
at OpenQA.Selenium.Remote.RemoteWebDriver.Execute(DriverCommand driverCommandToExecute, Dictionary`2 parameters) in e:\Projects\WebDriver\trunk\remote\client\src\csharp\webdriver-remote-client\RemoteWebDriver.cs: line 727
at OpenQA.Selenium.Remote.RemoteWebElement.FindElement(String mechanism, String value) in e:\Projects\WebDriver\trunk\remote\client\src\csharp\webdriver-remote-client\RemoteWebElement.cs: line 570
at OpenQA.Selenium.Remote.RemoteWebElement.FindElementByXPath(String xpath) in e:\Projects\WebDriver\trunk\remote\client\src\csharp\webdriver-remote-client\RemoteWebElement.cs: line 458
at OpenQA.Selenium.By.<>c__DisplayClasse.<XPath>b__c(ISearchContext context) in e:\Projects\WebDriver\trunk\common\src\csharp\webdriver-common\By.cs: line 119
at OpenQA.Selenium.By.FindElement(ISearchContext context) in e:\Projects\WebDriver\trunk\common\src\csharp\webdriver-common\By.cs: line 227
at OpenQA.Selenium.Remote.RemoteWebElement.FindElement(By by) in e:\Projects\WebDriver\trunk\remote\client\src\csharp\webdriver-remote-client\RemoteWebElement.cs: line 267
at IntegrationTests.WebForm1TestFixture.ShouldSelectItemOneThenItemTwo() in WebForm1TestFixture.cs: line 25
如果我更改测试使用ChromeDriver，则测试通过。在我看来，这样意味着它可以是一个与InternetExplorerDriver或Internet Explorer浏览器本身的问题。有谁知道，如果有什么我可以做的就是这一轮（该网站将在IE由最终用户使用，因此更改浏览器是不可能的，不幸的是）？
If I change the test to use a ChromeDriver then the test passes. It seems to me like this means it is either a problem with the InternetExplorerDriver or the Internet Explorer browser itself. Does anybody know which and if there's anything I can do to get round this (the site will be used in IE by the end users, so changing browsers isn't possible, unfortunately)?
编辑：目前的变通，我用的就是把一个 Thread.sleep代码（）列表中已被选中之后;这个工作，但显然不是一个理想的解决方案。
The current work-around that I am using is to put a Thread.Sleep() after the list has been selected; this works but obviously isn't an ideal solution.
推荐答案
下面是我最终落实的格局。
Below is the pattern I ended up implementing.
每个项目*。选择（）我已经实现了一个等待后：
After each item*.Select() I've implemented a wait:
IWait<IWebDriver> wait = new MyCustomWebDriverWait(driver, TimeSpan.FromSeconds(10));
wait.Until(driver => <some-condition-to-wait-for>);
其中<有的条件到等待换>是确定该项目的选择已经完成（例如，通过检查页面上的其他控制已被更新，例如
Where <some-condition-to-wait-for> is a way of determining that the item selection has finished (for example, by checking that another control on the page has been updated, e.g.
wait.Until(driver => driver.FindElement(By.Id("someLabelId")).Text == "expectedValue")`.
MyCustomWebDriverWait 是一个类实现 IWAIT< IWebDriver> ，是几乎相同的类，只抓到 StaleElementReferenceException 以及 NotFoundException （这意味着改变<$ C类型$ C> lastException 从 NotFoundException 到 WebDriverException 。
MyCustomWebDriverWait is a class that implements IWait<IWebDriver> and is almost identical to the WebDriverWait class, only it catches StaleElementReferenceException as well as NotFoundException (which meant changing the type of lastException from NotFoundException to WebDriverException.
您可以阅读我是如何在指向这个方向由丹尼尔·瓦格纳厅硒，谷歌用户群的。
You can read how I was pointed in this direction by Daniel Wagner-Hall on the Selenium-users google group here.
这篇关于硒2 StaleElementReferenceException使用的DropDownList当的AutoPostBack随着InternetExplorerDriver的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！