selenium - org.openqa.selenium.NoSuchElementException : no such element

Question

运行 Selenium WebDriver 2.37.1

我在运行测试时遇到间歇性问题并收到以下错误:

org.openqa.selenium.NoSuchElementException: no such element

有时测试会通过，但大多数时候会失败。下面是堆栈跟踪:

org.openqa.selenium.NoSuchElementException: no such element  
(Session info: chrome=31.0.1650.57)
(Driver info:
chromedriver=2.6.232923,platform=Windows NT 6.1 SP1 x86_64) 
(WARNING:
The server did not provide any stacktrace information) 
Command duration or timeout: 10.04 seconds 
For documentation on this error, please visit:
http://seleniumhq.org/exceptions/no_such_element.html 
Build info:
version: '2.34.0', revision:
'11cd0ef93615408e0b6b3bfa28defe125906461a', time: '2013-08-06
11:43:14' 
System info: os.name: 'Windows 7', os.arch: 'amd64',
os.version: '6.1', java.version: '1.7.0_45' 
Session ID:
2375dca8adea8bb6962b0c87861cdd59 
Driver info:
org.openqa.selenium.chrome.ChromeDriver 
Capabilities

下面是我执行测试的代码:

@Test
public void loginPage(){

    chrome.get("http://thisisafakeurl.com");
    //entering username
    WebElement usernameField = chrome.findElement(By.cssSelector("input[type='text'][id='usernameInput']"));
        usernameField.sendKeys("fakeusername");
    //entering password
    WebElement passwordField = chrome.findElement(By.cssSelector("input[id='passwordInput']"));
        passwordField.sendKeys("fakepassword");
    //clicking submit button
    chrome.findElement(By.cssSelector("input#loginBtn.rightButton")).click();

    chrome.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);

    //asserting a css selector. Not really needed. Just thrown in to learn.
   // WebElement blankProjectLocator = chrome.findElement(By.cssSelector("li.iconGridItem[data-id='5']"));
   // Assert.assertEquals("5", blankProjectLocator.getAttribute("data-id"));

    //Clicking the Blank Project button

    Actions actions = new Actions(chrome);
    WebElement item1 = chrome.findElement(By.xpath("//*[@id=\"templateGrid\"]/li[2]/img[1]"));
    WebElement item2 = chrome.findElement(By.xpath("//*[@id=\"templateGrid\"]/li[2]/img[2]"));
    WebElement item3 = chrome.findElement(By.xpath("//*[@id=\"templateGrid\"]/li[2]/header/span"));
    WebElement item4 = chrome.findElement(By.xpath("//*[@id=\"templateGrid\"]/li[2]"));

    actions.moveToElement(item4)
           .moveToElement(item1)
           .moveToElement(item2)
           .moveToElement(item3)
           .click().build().perform();

    chrome.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS);





    //Dragging the Click Area component onto the canvas
    WebElement listContainer = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div"));
    WebElement componentList = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul"));
    WebElement clickArea = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[1]"));
    WebElement arrowHead = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[1]/div[1]"));
    WebElement imageHolderClickArea = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[1]/div[1]/div"));
    WebElement componentNameClickArea = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[1]/div[2]"));


    WebElement canvas = chrome.findElement(By.xpath("//*[@id=\"page-c3\"]"));

    actions.moveToElement(listContainer)
           .moveToElement(componentList)
           .clickAndHold(clickArea)
           .moveToElement(arrowHead)
           .moveToElement(imageHolderClickArea)
           .moveToElement(componentNameClickArea)
           .moveToElement(canvas)
           .release().perform();

    chrome.manage().timeouts().implicitlyWait(5, TimeUnit.SECONDS);






    //Dragging the close button onto the canvas

    WebElement listContainerClose = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div"));
    WebElement componentListClose = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul"));
    WebElement closeButton = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[2]"));
    WebElement componentThumb = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[2]/div[1]"));
    WebElement imageHolderCloseButton = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[2]/div[1]/div"));
    WebElement componentNameCloseButton = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[2]/div[2]"));

    WebElement canvas1 = chrome.findElement(By.xpath("//*[@id=\"page-c3\"]"));

    actions.clickAndHold(closeButton)
            .moveToElement(listContainerClose)
            .moveToElement(componentListClose)
            .moveToElement(componentThumb)
            .moveToElement(imageHolderCloseButton)
            .moveToElement(componentNameCloseButton)
            .moveToElement(canvas1)
            .release().perform();

    //WebElement xAxisClose = chrome.findElement(By.xpath("//*[@id=\"c358\"]"));
    //xAxisClose.clear();
    //xAxisClose.sendKeys("240");

    //WebElement yAxisClose = chrome.findElement(By.xpath("//*[@id=\"c359\"]"));
    //yAxisClose.clear();
    //yAxisClose.sendKeys("5");






    //Dragging the video component onto the canvas

    WebElement listContainerVideo = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div"));
    WebElement componentListVideo = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul"));
    WebElement videoComponent = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[3]"));
    WebElement componentThumbVideo = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[3]/div[1]"));
    WebElement componentNameVideo = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[3]/div[2]"));

    WebElement canvas2 = chrome.findElement(By.xpath("//*[@id=\"page-c3\"]"));

    actions.clickAndHold(videoComponent)
            .moveToElement(listContainerVideo)
            .moveToElement(componentListVideo)
            .moveToElement(componentThumbVideo)
            .moveToElement(componentNameVideo)
            .moveToElement(canvas2)
            .release().perform();


    chrome.manage().timeouts().implicitlyWait(5, TimeUnit.SECONDS);






    //Dragging the Text component onto the canvas

    WebElement listContainerText = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div"));
    WebElement componentListText = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul"));
    WebElement textComponent = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[4]"));
    WebElement componentThumbText = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[4]/div[1]"));
    WebElement componentNameText = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div/ul/li[4]/div[2]"));

    WebElement canvas3 = chrome.findElement(By.xpath("//*[@id=\"page-c3\"]"));

    actions.clickAndHold(textComponent)
            .moveToElement(listContainerText)
            .moveToElement(componentListText)
            .moveToElement(componentThumbText)
            .moveToElement(componentNameText)
            .moveToElement(canvas3)
            .release().perform();

堆栈跟踪中的可点击链接将我指向以下代码行:

 WebElement listContainer = chrome.findElement(By.xpath("//*[@id=\"componentsDiv\"]/div/div/div"));

所以在测试之前可以点击Blank Project按钮。

根据我的调查，我可能遇到了一些同步问题，因为它是间歇性的。我是否需要包装 try/catch 异常而不是超时等待？或者我是否将它们放置在代码中不正确的位置？

任何人都可以帮助或建议我可能出错的地方吗？

Answer 1

正如 Yuvaraj HK 所提到的，在代码中仅使用一次隐式等待就足够了。它会隐式等待您尝试在代码中查找的每个元素。

chrome.manage().timeouts().implicitlyWait(30, TimeUnit.SECONDS);

但请尽量保持隐式等待时间尽可能短，因为这可能会增加代码执行时间..

在某些情况下，元素可能需要 30 秒以上才能可见，在这种情况下可以使用显式等待。

WebDriverWait some_element = new WebDriverWait(driver,100); 
some_element.until(ExpectedConditions.visibilityOfElementLocated(By.id("id_of_some_element")));
//do anything you want with some_element

我强烈建议使用cssSelectors通过 xpath。 This article might help .
即使使用 xpath，也尝试使用较短的路径。 使用 id 并不是访问元素的唯一方法。它的父级可能具有唯一的类名或其他属性，您可以使用它们来创建高效的 xpaths 或 cssSelectors。