只要我使用 PageObject 模式，我就想知道我应该在哪里等待动态页面上的元素。假设我们有测试方法和 pageObject 类。我应该做类似的事情吗(在测试方法中):

1. 点击按钮
2. 等待元素显示
3. 验证元素(包含例如方法 isElementDisplayed())

或者也许还有其他好的做法来等待元素？也许我们应该在 PageObject.class 的 isElementDisplayed 方法中等待元素？

最佳答案

您应该等待页面对象类中的元素，而不是测试类中的元素，因为您的元素应该在页面对象类中定义，测试类应该对任何元素、选择器或类似元素一无所知。测试，恕我直言，应该只包含描述测试流程的方法调用链，所有与网站和底层 DOM 的交互都应该在页面对象类中进行。

所以等待某个元素出现的过于冗长的方法可能是这样的:

private final By yourElement = By.id("id");
@Override
public void isLoaded() throws Error {
    new FluentWait<WebDriver>(driver)
            .withTimeout(60, TimeUnit.SECONDS)
            .pollingEvery(1, TimeUnit.SECONDS)
            .ignoring(NoSuchElementException.class)
            .ignoring(StaleElementReferenceException.class)
            .until(new Function<WebDriver, Boolean>() {
                @NotNull
                @Override
                public Boolean apply(WebDriver webDriver) {
                    WebElement element = driver.findElement(yourElement);
                    return element != null && element.isDisplayed();
                }
            });
}

简而言之，函数如果轮询 DOM 60 秒(每 1 秒)以查看元素是否存在于 DOM 中并且可见(意味着高度和宽度大于 1px)。如果该元素存在(并显示)，该函数返回找到的元素并停止轮询(尽管 isLoaded() 方法在此特定情况下不返回该元素)。

忽略 NoSuchElementException 是有意义的，findElement 方法会在找不到元素的情况下抛出该异常，而 StaleElementException 表示对元素的引用现在是“陈旧的”——该元素不再出现在页面的 DOM 中。这通常意味着，某些东西(最常见的是 JS)修改了 DOM 并且引用不再有效，因此 WebDriver 需要再次查找它。

当然，更短的代码也能达到目的，比如:

    new WebDriverWait(driver, 60)
            .until(ExpectedConditions.visibilityOf(someWebElement));

documentation实际上在这方面相当不错。

编辑:对评论的回答:

OK, understood. But what if element is present after clicking on some button etc.?

假设您有一个场景，您有一个按钮，单击该按钮后会出现一个文本框，您想要与之交互。

public class PageObject extends LoadableComponent<PageObject>{

    public PageObject() throws Exception {
        driver = getWebDriver();
        PageFactory.initElements(driver, this);
        isLoaded();
    }
    private WebDriver driver = null;

    @FindBy(id = "yourButton")
    private WebElement button;

    @FindBy(id = "textBoxThatAppears")
    private WebElement txtBox;

    @Override
    public void isLoaded() throws Error {
        // Initial loading, called when creating the page object to make sure that the page is loaded to a state where it is ready to interact with us, in our case it means that button is present in DOM and visible.
        waitForVisibility(button);
    }

    private void waitForVisibility(WebElement element) throws Error{
           new WebDriverWait(driver, 60)
                .until(ExpectedConditions.visibilityOf(element));
    }

    public void clickButton(){
        button.click();

    }

    public void interactWithTextbox(String text){
        // Wait for txtBox to be visible, then send text
        waitForVisibility(txtBox);
        txtBox.sendKeys(text);

       // EDIT 27.04.14: 
       // Actually you should not do the assertion here or anywhere in 
       // the pageObject, because when reusing the method in some other test, you might
       // not want to assert, you might wonder that why wouldn't you assert some 
       // specific condition every time, but I would throw that question right back 
       // to you and ask: What is the point of checking the exact same thing over and 
       // over again. There are 2 things, firstly the assertion takes resources (and
       // that can become important when test suite grows, secondly your tests can 
       // simply start failing at the same point when one little condition is not as
       // it should be. Also, having the asserts in the test, makes the test more
       // readable and understandable for others.
         // end edit 27.04.14
        // Next line is no longer recommended by this answer.
         // assert that something happened that you expected.
    }

}

现在你的测试类:

public void TestClass {

     @Test
     public void testClickButtonAndInteractWithTextbox(){
         // Initiate the page object
         Pageobject po = new PageObject();
         po.clickButtonAndWaitForTextbox();
         po.interactWithTextbox("blabla");
         // edit 27.04.14
         assertSomethingGoodHappened();
     }
}

关于java - 等待元素 - WebDriver - PageObject 模式，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/18843581/