Webdriver StaleElementReferenceException

January 26, 2012

  public void clickMakeSomeAttendeesOptional() {
    makeSomeAttendeesOptionalLink.click();
  }
  public void makeOptional(String name) {
    driver.findElement(String.format(REQUIRED_ATTENDEE_ICON, name))
        .click(); // StaleElementReferenceException here
  }

  public void clickMakeSomeAttendeesOptional() {
    makeSomeAttendeesOptionalLink.click();
    waitUntilVisible(optionalAttendeesLegend);
  }

WebDriverWait wait = new WebDriverWait(driver, timeout);
wait.until(ExpectedConditions.visibilityOfElementLocated(By.xpath(String.format(ATTENDEE, names.get(0)))); // StaleElementReferenceException here

// In concrete Page object

  public void waitUntilMonthViewIsDisplayed() {
    waitUntilVisible(By.id("mvEventContainer"));
  }

// In abstract parent


  protected RenderedWebElement waitUntilVisible(By locator) {
    WebDriverWait wait = new WebDriverWait(driver, 20);
    return (RenderedWebElement) wait.until(refreshed(ExpectedConditions.visibilityOfElementLocated(locator)));
  }




  private <T> ExpectedCondition<T> refreshed(final Function<WebDriver, T> originalFunction) {
    return new ExpectedCondition<T>() {
      @Override
      public T apply(WebDriver webdriver) {
        try {
          return originalFunction.apply(webdriver);
        } catch (StaleElementReferenceException sere) {
          throw new NoSuchElementException("Element stale.", sere);
        }
      }
    };
  }

  @FindBy(id = "tgCol0")
  private RenderedWebElement gridFirstColumn;

  public EventBubble clickGridFirstColumn() {
    gridFirstColumn.click(); // StaleElementReferenceException here
    return newEventBubble();
  }

  @Override
  public void click() {
    try {
      underlyingElement.click();
    } catch (StaleElementReferenceException sere) {
      againLocate();
      click();
    }
  }

  protected void againLocate() {
    underlyingElement = locator.locate();
  }

WebElement element = driver.findElement(...);
WebElement e2 = element.findElement(...);
e2.click();  // StaleElementReferenceException here

  protected OurWebElement(WebElement underlyingElement, Locator locator) {
    this.underlyingElement = underlyingElement;
    this.locator = locator;
  }

  @Override
  public WebElement findElement(By by) {
    try {
      return wrap(underlyingElement.findElement(by),
                  new FindElementLocator(this, by));
    } catch (StaleElementReferenceException sere) {
      againLocate();
      return findElement(by);
    }
  }

  protected void againLocate() {
    underlyingElement = locator.locate();
  }

// In Concrete PageObject class

  public void toggleCalendar(String name) {
    findElement( "//div[@class='t23']//div[text()='" + name + "']").click();

  }
  // In Abstract parent class
  protected WebElement findElement(By by) {
    return OurWebElement.wrap(driver.findElement(by), new OurWebElement.FindElementLocator(driver, by));
  }

Conclusion

Most of the time the StaleElementReferenceException can be addressed by waiting for something at the right time and this should be your first line of thought. Currently it can be that this is not enough though. Cases 2 - 5 should really be handled by WebDriver IMO. Waiting should always work. Elements provided by @FindBy should always work (when I just created the page object). And the result of my tests should not depend on whether I’m lucky or not

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Book review: The Mythical Man-Month (by Frederick P. Brooks)

January 8, 2011

The book is 35 years old and it shows in many places. What is fascinating in the book is not so much the solutions that they came up with at that time (obviously some technology hasn’t been around at that time), but that many of the problems they faced are still problems today.

For example in the chapter “Why did the tower of Babel fail?” he writes:

“So it is today. Schedule disaster, functional misfits, and system bugs all arise because the left hand doesn’t know what the right hand is doing. As work proceeds, the several teams slowly change the functions, sizes, and speed of their own programs, and they explicitly or implicitly change their assumptions about the inputs available and the uses to be made of outputs.”

His suggestion to using the telephone often, regular project meetings and a (physical) workbook (that needs to updated by each engineer) are outdated of course. However it is interesting to see, that he pointed his finger on a big problem that is still valid today. We’re still looking to solve that. In the meantime, a lot of things have addressed these concerns: Javadoc, Wikis, Design by contract, Unit tests etc.

So if you decide to read this book and expect to get solutions out of it, you will probably be disappointed. But you will be amazed, that many of the big problems from back then are actually still big problems today. Even more, they seem to be problems that still catch projects by surprise as they rediscover them. In that regard, the time spent reading this small book is time very well spent!

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Go social!

March 30, 2010

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Nice Haircut!

January 22, 2010

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Swiss Softball National Team Training

January 18, 2010

I used these kinds of pictures for the Trainingsday of the Swiss National Softball Team to explain some common mistakes. All the pictures here [pdf], in case somebody wants to have a closer look at them later on.

Andi rolling hands over

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Some Christmas Cards

December 24, 2009

Merry Christmas to everybody.

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Sweet child of mine - violin

October 5, 2009

Sometimes, one word is enough: Wow!!!

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Meteor come - BOOM

September 9, 2009

Meteor come -> Boom | Agile come -> Boom

No more defects. No more test phase. No more testers.

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And why did you become extinct?

September 4, 2009

And why did you guys become extinct?

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First Swiss Testing Night - Impressions

June 12, 2009

Here are some impressions from the first Swiss Testing Night:

Screenshot Swiss Testing Night Website

The Swiss Testing Night Programme. Three quarters of an hour to torment QA people with ideas about Testing by a developer.

Intro by Adrian Zwingli

I think this was the moment I was the most nervous: Being introduced by Adrian Zwingli (Chief Organizer). Everybody is ready, waiting for you. Then you realize: There’s no way back - only one way to go. That’s when most of the nervousness goes away - kind of like in baseball when you take the mound.

Setting up the stage

Setting things up. The remote control didn’t work, probably because the infrared receiver was blocked by the podium. And no headset style microphone - the room was set up for a speaker talking from behind the podium. No chance I was going to do that though. So I turned the podium sideways and picked the micro up - Rockstar style

Me apologizing to our sponsor (HP)

I think that’s the moment I realized that saying “one of the reason for the existence of bugs are bug tracking tools” might not sit too well with our sponsor HP - who sells Quality Center and Winrunner among other things.

Oh well - sometimes you step on somebodys toe - life goes on. That plus HP has a mighty big toe.

One of my favorite slides

This is one of my favorite slides (introducing the second part of the speech). A reference to Starship Troopers (how could you leave out a reference to the best movie ever, if your topic is “Crusade against Bugs”)?

Not enough chairs guaranteed at least a partial standing ovation at the end

A misunderstanding between the organizers and the location provided for about 20 chairs - the other 80 people had to stand the whole time. Before the speech I thought about having people rotate after every part of the speech. That way most people would get at least 15 min of sitting time. I’m afraid I forgot. Not that it was a good idea to begin with.

All the photos here were taken by Stephan Wiesner (@Stephan: If you’re reading - thanks a lot for letting me use them on my site).

Posted by Jerome Mueller, 3 Comments