我想确保在webdriver开始做事情之前,一个元素是存在的。
我正在尝试这样做:
WebDriverWait wait = new WebDriverWait(driver, new TimeSpan(0, 0, 5));
wait.Until(By.Id("login"));
我主要是挣扎如何设置匿名功能…
我想确保在webdriver开始做事情之前,一个元素是存在的。
我正在尝试这样做:
WebDriverWait wait = new WebDriverWait(driver, new TimeSpan(0, 0, 5));
wait.Until(By.Id("login"));
我主要是挣扎如何设置匿名功能…
当前回答
使用Mike Kwan提供的解决方案可能会对整体测试性能产生影响,因为隐式等待将在所有FindElement调用中使用。
很多时候,您希望FindElement在一个元素不存在时立即失败(您正在测试一个畸形的页面、缺失的元素等)。使用隐式等待,这些操作将在抛出异常之前等待整个超时到期。默认的隐式等待设置为0秒。
我写了一个小扩展方法到IWebDriver,它添加了一个超时(秒)参数FindElement()方法。这是不言而喻的:
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);
}
}
我没有缓存WebDriverWait对象,因为它的创建非常便宜,这个扩展可以同时用于不同的WebDriver对象,我只在最终需要的时候做优化。
用法很简单:
var driver = new FirefoxDriver();
driver.Navigate().GoToUrl("http://localhost/mypage");
var btn = driver.FindElement(By.CssSelector("#login_button"));
btn.Click();
var employeeLabel = driver.FindElement(By.CssSelector("#VCC_VSL"), 10);
Assert.AreEqual("Employee", employeeLabel.Text);
driver.Close();
其他回答
// 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"));
});
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();
使用Rn222的答案和akns1的答案来使用ISearchContext,返回单个元素或列表。并且可以指定元素的最小数量:
public static class SearchContextExtensions
{
/// <summary>
/// Method that finds an element based on the search parameters within a specified timeout.
/// </summary>
/// <param name="context">The context where this is searched. Required for extension methods</param>
/// <param name="by">The search parameters that are used to identify the element</param>
/// <param name="timeOutInSeconds">The time that the tool should wait before throwing an exception</param>
/// <returns> The first element found that matches the condition specified</returns>
public static IWebElement FindElement(this ISearchContext context, By by, uint timeOutInSeconds)
{
if (timeOutInSeconds > 0)
{
var wait = new DefaultWait<ISearchContext>(context);
wait.Timeout = TimeSpan.FromSeconds(timeOutInSeconds);
return wait.Until<IWebElement>(ctx => ctx.FindElement(by));
}
return context.FindElement(by);
}
/// <summary>
/// Method that finds a list of elements based on the search parameters within a specified timeout.
/// </summary>
/// <param name="context">The context where this is searched. Required for extension methods</param>
/// <param name="by">The search parameters that are used to identify the element</param>
/// <param name="timeoutInSeconds">The time that the tool should wait before throwing an exception</param>
/// <returns>A list of all the web elements that match the condition specified</returns>
public static IReadOnlyCollection<IWebElement> FindElements(this ISearchContext context, By by, uint timeoutInSeconds)
{
if (timeoutInSeconds > 0)
{
var wait = new DefaultWait<ISearchContext>(context);
wait.Timeout = TimeSpan.FromSeconds(timeoutInSeconds);
return wait.Until<IReadOnlyCollection<IWebElement>>(ctx => ctx.FindElements(by));
}
return context.FindElements(by);
}
/// <summary>
/// Method that finds a list of elements with the minimum amount specified based on the search parameters within a specified timeout.<br/>
/// </summary>
/// <param name="context">The context where this is searched. Required for extension methods</param>
/// <param name="by">The search parameters that are used to identify the element</param>
/// <param name="timeoutInSeconds">The time that the tool should wait before throwing an exception</param>
/// <param name="minNumberOfElements">
/// The minimum number of elements that should meet the criteria before returning the list <para/>
/// If this number is not met, an exception will be thrown and no elements will be returned
/// even if some did meet the criteria
/// </param>
/// <returns>A list of all the web elements that match the condition specified</returns>
public static IReadOnlyCollection<IWebElement> FindElements(this ISearchContext context, By by, uint timeoutInSeconds, int minNumberOfElements)
{
var wait = new DefaultWait<ISearchContext>(context);
if (timeoutInSeconds > 0)
{
wait.Timeout = TimeSpan.FromSeconds(timeoutInSeconds);
}
// Wait until the current context found the minimum number of elements. If not found after timeout, an exception is thrown
wait.Until<bool>(ctx => ctx.FindElements(by).Count >= minNumberOfElements);
// If the elements were successfuly found, just return the list
return context.FindElements(by);
}
}
使用示例:
var driver = new FirefoxDriver();
driver.Navigate().GoToUrl("http://localhost");
var main = driver.FindElement(By.Id("main"));
// It can be now used to wait when using elements to search
var btn = main.FindElement(By.Id("button"), 10);
btn.Click();
// This will wait up to 10 seconds until a button is found
var button = driver.FindElement(By.TagName("button"), 10)
// This will wait up to 10 seconds until a button is found, and return all the buttons found
var buttonList = driver.FindElements(By.TagName("button"), 10)
// This will wait for 10 seconds until we find at least 5 buttons
var buttonsMin = driver.FindElements(By.TagName("button"), 10, 5);
driver.Close();
WebDriverWait将不生效。
var driver = new FirefoxDriver(
new FirefoxOptions().PageLoadStrategy = PageLoadStrategy.Eager
);
driver.Navigate().GoToUrl("xxx");
new WebDriverWait(driver, TimeSpan.FromSeconds(60))
.Until(d => d.FindElement(By.Id("xxx"))); // A tag that close to the end
一旦页面是“交互式的”,这将立即抛出异常。我不知道为什么,但是超时就好像它不存在一样。
也许SeleniumExtras。WaitHelpers很管用,但我没试过。这是官方的,但它被拆分为另一个NuGet包。你可以参考c# Selenium 'ExpectedConditions is obsolete'。
我使用FindElements并检查Count == 0。如果为真,则使用await Task.Delay。这真的不是很有效。
使用c#扩展方法:我们可以解决等待直到元素可见的问题。 一个特定元素的最大reties是100。
public static bool WaitForElementToBeVisible(IWebDriver browser, By by)
{
int attemptToFindElement = 0;
bool elementFound = false;
IWebElement elementIdentifier = null;
do
{
attemptToFindElement++;
try
{
elementIdentifier = browser.FindWebElement(by);
elementFound = (elementIdentifier.Displayed && elementIdentifier.Enabled) ? true : false;
}
catch (Exception)
{
elementFound = false;
}
}
while (elementFound == false && attemptToFindElement < 100);
return elementFound;
}