Selenium C#中的显式等待不起作用。什么是错的？

Question

所以我有显式等待的问题。我不想用线。睡眠（）。这是一个简单的html" target="_blank">测试，它打开一个页面，然后来回移动。加载此页面大约需要2-3秒，我希望以动态方式（测试）完成此操作。希望我不是太糊涂。我做了很多研究，但都不管用，也许我做错了什么。（我正在使用Resharper运行单元测试）

这里我还有一个解决方案：

https://www.dropbox.com/s/1k5vjc5czvmdd3u/ConsoleApplication2.rar?dl=0

我正在使用FindElement方法的扩展，所以我相信调用这个方法并自行等待会很容易。我有一些解释注释在解决方案。如果有人能给我一些帮助，我将不胜感激。（抱歉英语不太好）。

using System;
using System.Threading;
using ConsoleApplication2.Extensions;
using NUnit.Framework;
using OpenQA.Selenium;
using OpenQA.Selenium.Chrome;
using OpenQA.Selenium.Support.UI;

namespace ConsoleApplication2
{
    class UnitTest1
    {
        private IWebDriver driver = new ChromeDriver();
        [SetUp]
        public void Initialize()
        { 
            driver.Url = "some url";
            Thread.Sleep(3500);
           // driver.Manage().Timeouts().ImplicitlyWait(TimeSpan(20));

        }

       [Test]
        public void CheckBackForward()
        {
            //Go to first page in Online Help
            driver.FindElement(By.XPath("//span/ul/li/span/a")).Click();
            // So if I am commenting this Thread.Sleep
            // it will throw an exception at the extension method at line 13 at "@by"
            // I've also checked this without extension method but still the same problem. It doesn'w wait at all, it will throw this 
            // exception as soon as FindElement method is called.
            // I know that I shouldn't mix explicit waits with implicit ones.
            //Thread.Sleep(1500);
            //Store title
            var title_text = driver.FindElement(By.XPath("//div[@id='shellAreaContent']/div/div[2]/ol/li[3]/span"),60).Text;
            //Check if Back is enabled
            Assert.IsTrue(driver.FindElement(By.XPath("//div[3]/a/span")).Enabled);
            //Go back
            driver.FindElement(By.XPath("//div[3]/a/span")).Click();
            //Check if Forward is enabled
            Assert.IsTrue(driver.FindElement(By.XPath("//div[4]/a/span")).Enabled);
            //Go forward
            driver.FindElement(By.XPath("//div[4]/a/span")).Click();
            //Store title
            var title_text2 = driver.FindElement(By.XPath("//div[@id='shellAreaContent']/div/div[2]/ol/li[3]/span")).Text;
            //Check if you are on the same page
            Assert.AreEqual(title_text2,title_text);
        }



        [TearDown]
        public void EndTest()
        {
            driver.Quit();
        }

    }
}

这是分机：

using System;
using OpenQA.Selenium;
using OpenQA.Selenium.Support.UI;

namespace ConsoleApplication2.Extensions
{
    public static class Extension
    {
        public static IWebElement FindElement(this IWebDriver driver, By by, int timeoutInSeconds)
        {
            if (timeoutInSeconds <= 0) return driver.FindElement(@by);
            var wait = new WebDriverWait(driver, TimeSpan.FromSeconds(timeoutInSeconds));
            return wait.Until(drv => drv.FindElement(@by));
        }



    }
}

Answer 1

我用Selenium编码了6个月，我有和你一样的问题。我创建了这个扩展方法，它每次都对我有效。

代码所做的是：在20秒内，它每500ms检查一次元素是否出现在页面上。如果20秒后没有找到，它将引发异常。这将帮助您进行动态等待。

  public static class SeleniumExtensionMethods {
      public static WebDriverWait wait = new WebDriverWait(driver, TimeSpan.FromSeconds(20));
      public static void SafeClick(this IWebElement webElement) {
          try {
              wait.Until(ExpectedConditions.ElementToBeClickable(webElement)).Click();
          } catch (TargetInvocationException ex) {
              Console.WriteLine(ex.InnerException);
          }

      }

然后替换您的代码：

driver.FindElement(By.XPath("//span/ul/li/span/a")).Click();

与：

IWebElement x = driver.FindElement(By.XPath("//span/ul/li/span/a"));
x.SafeClick();