如何等待Selenium中的元素不再存在

问题描述

我正在测试用户单击删除按钮的UI，表条目消失。因此，我希望能够检查表条目不再存在。

I am testing a UI in which the user clicks a delete button and a table entry disappears. As such, I want to be able to check that the table entry no longer exists.

我尝试使用 ExpectedConditions.not（）反转 ExpectedConditions.presenceOfElementLocated（），希望它意味着期望不存在指定的元素。我的代码是这样的：

I have tried using ExpectedConditions.not() to invert ExpectedConditions.presenceOfElementLocated(), hoping that it would mean "expect that there is not a presence of the specified element". My code is like so:

browser.navigate().to("http://stackoverflow.com");
new WebDriverWait(browser, 1).until(
        ExpectedConditions.not(
                ExpectedConditions.presenceOfElementLocated(By.id("foo"))));

然而，我发现即使这样做，我得到 TimeoutExpcetion 由 NoSuchElementException 引起，表示元素foo不存在。当然，没有这样的元素是我想要的，但我不想抛出异常。

However, I found that even doing this, I get a TimeoutExpcetion caused by a NoSuchElementException saying that the element "foo" does not exist. Of course, having no such element is what I want, but I don't want an exception to be thrown.

那么我怎么能等到一个元素不再存在？我更喜欢一个不依赖于捕获异常的示例（如我所知，异常应该抛出异常行为）。

So how can I wait until an element no longer exists? I would prefer an example that does not rely on catching an exception if at all possible (as I understand it, exceptions should be thrown for exceptional behavior).

推荐答案

您还可以使用 -

new WebDriverWait(driver, 10).until(ExpectedConditions.invisibilityOfElementLocated(locator));

如果你查看它的来源，你可以看到 NoSuchElementException 和 staleElementReferenceException 。

If you go through the source of it you can see that both NoSuchElementException and staleElementReferenceException are handled.

/**
   * An expectation for checking that an element is either invisible or not
   * present on the DOM.
   *
   * @param locator used to find the element
   */
  public static ExpectedCondition<Boolean> invisibilityOfElementLocated(
      final By locator) {
    return new ExpectedCondition<Boolean>() {
      @Override
      public Boolean apply(WebDriver driver) {
        try {
          return !(findElement(locator, driver).isDisplayed());
        } catch (NoSuchElementException e) {
          // Returns true because the element is not present in DOM. The
          // try block checks if the element is present but is invisible.
          return true;
        } catch (StaleElementReferenceException e) {
          // Returns true because stale element reference implies that element
          // is no longer visible.
          return true;
        }
      }

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