我混淆了匿名函数和谓词。这里有一个小帮手方法:

   WebDriverWait wait;
    private void waitForById(string id)
    {
        if (wait == null)
            wait = new WebDriverWait(driver, new TimeSpan(0, 0, 5));

        //wait.Until(driver);
        wait.Until(d => d.FindElement(By.Id(id)));
    }

下面是Loudenvier解决方案的一个变体，它也适用于获得多个元素:

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

    public static ReadOnlyCollection<IWebElement> FindElements(this IWebDriver driver, By by, int timeoutInSeconds)
    {
        if (timeoutInSeconds > 0)
        {
            var wait = new WebDriverWait(driver, TimeSpan.FromSeconds(timeoutInSeconds));
            return wait.Until(drv => (drv.FindElements(by).Count > 0) ? drv.FindElements(by) : null);
        }
        return driver.FindElements(by);
    }
}

我正在用这个，效果很好:

public static bool elexists(By by, WebDriver driver)
{
    try
    {
        driver.FindElement(by);
        return true;
    }
    catch (NoSuchElementException)
    {
        return false;
    }
}

public static void waitforelement(WebDriver driver, By by)
{
    for (int i = 0; i < 30; i++)
    {
        System.Threading.Thread.Sleep(1000);
        if (elexists(by, driver))
        {
            break;
        }
    }
}

当然，您可以添加超过30次的尝试，并将周期缩短到1秒以内进行检查。

用法:

waitforelement(driver, By.Id("login"));
IWebElement login = driver.FindElement(By.Id("login"));
login.Click();

// Wait up to 5 seconds with no minimum for a UI element to be found
WebDriverWait wait = new WebDriverWait(_pagedriver, TimeSpan.FromSeconds(5));
IWebElement title = wait.Until<IWebElement>((d) =>
{
    return d.FindElement(By.ClassName("MainContentHeader"));
});

您不希望在元素更改之前等待太长时间。在这段代码中，webdriver在继续之前最多等待2秒。

WebDriverWait wait = new WebDriverWait(driver, TimeSpan.FromMilliseconds(2000));
wait.Until(ExpectedConditions.VisibilityOfAllElementsLocatedBy(By.Name("html-name")));

下面是如何在Selenium中等待一个条件:

    WebDriverWait wait = new WebDriverWait(m_driver, TimeSpan.FromSeconds(10));
    wait.Until(d => ReadCell(row, col) != "");

ReadCell(row, col) != ""可以是任何条件。这样做是因为:

它是我的 允许内联