Implicit and Explicit waits in Selenium WebDriwer, how to.

How to use waits in Selenium WebDriver

1. YOU ARE DOING IT WRONG
ALL THE TIME
The Great Battle of Selenium Waits

2. Speaker Info
Yaroslav Pernerovsky,
Ukraine

Automation Team Lead,
GlobalLogic

/in/yaroslav-pernerovsky-0559b51
/yaroslav.pernerovsky

3. Problem
Implicit waits are a terrible mistake I've made
and I apologies for them
Simon Stewart, d
Creator of WebDriver

4. Problem

5. Problem

6. Problem

7. Problem

8. @Test
public void simpleAction() {
driver.get("http://www.google.com" );
driver.findElement(By.name("q"))
.sendKeys("Search String" + Keys.ENTER);
driver.findElement(By.cssSelector("h3.r"))
.click();
}
Real Case

9. Real Case

10. Real Case

11. Custom Wait
while(true) {
if (System.currentTimeMillis()-startTime > timeout){
throw new TimeoutException();
}
try {
return driver.findElement(locator);
}
catch (NoSuchElementException e) {}
Thread.sleep(500);
}

12. WebDriver waits
chromedriver
geckodriver
IEDriverServer
Implicit waits here Explicit waits here

13. Implicit Waits
driver.manage().timeouts(). implicitlyWait(10, TimeUnit.SECONDS);

driver.manage().timeouts().pageLoadTimeout(10, TimeUnit.SECONDS);
driver.manage().timeouts(). setScriptTimeout(10, TimeUnit.SECONDS);

14. Implicit Waits
driver.findElement()
•Wait until element appeared in DOM
•Return first element if more than one present
•Throws NoSuchElementException

15. Implicit Waits
driver.findElements()
•Wait until at least one element appeared in DOM
•Return collection of all found elements
•Return empty collection if no elements found

16. Implicit Waits Common Issue
public boolean isElementPresent(By locator) {
return driver.findElements(locator).size() > 0;
}
if (isElementPresent(login))
driver.findElement(login).click();
if (!isElementPresent(login))
driver.findElement(logout).click();

17. Implicit Waits Common Issue
public boolean isElementNotPresent(By locator) {

driver.manage().timeouts()
.implicitlyWait(0, TimeUnit.SECONDS);

boolean result= driver.findElements(locator).size() > 0;

driver.manage().timeouts()
.implicitlyWait(defaultTimeOut, TimeUnit.SECONDS);

return result;
}

18. Explicit Waits
WebDriverWait wait = new
WebDriverWait(driver, 10);

wait.until(driver ->
driver.findElement(locator));

wait.until(ExpectedConditions
.presenceOfElementLocated (locator));

http://seleniumhq.github.io/selenium/docs/api/java/org/openqa/selenium/support/ui/ExpectedConditions.html

19. What's wrong?
wait.until(driver ->
driver.findElement(locator));

20. WebDriver Exceptions and RemoteWebDriver

21. Solution?
wait.until(driver ->
driver.findElements( locator).size() > 0);

22. Mixed waits issues

23. What if?
wait = new WebDriverWait(driver,5);
driver.manage().timeouts()
.implicitlyWait(10, TimeUnit.SECONDS);

wait.until(ExpectedConditions
.presenceOfElementLocated (locator);
How long will Selenium wait ?
5 15
C: 10 25

24. Why?
public static ExpectedCondition<WebElement> presenceOfElementLocated( final By locator) {
return new ExpectedCondition<WebElement>() {
@Override
public WebElement apply(WebDriver driver) {
return findElement(locator, driver);
}
...
private static WebElement findElement(By by, WebDriver driver) {
try {
return driver.findElements(by).stream().findFirst().orElseThrow(
() -> new NoSuchElementException( "Cannot locate an element using " + by));
} catch (NoSuchElementException e) {
throw e;
} catch (WebDriverException e) {
log.log(Level.WARNING,
String.format("WebDriverException thrown by findElement(%s)" , by), e);
throw e;
}
}

25. What if?
wait = new WebDriverWait(driver,5);
driver.manage().timeouts()
.implicitlyWait(10, TimeUnit.SECONDS);

wait.until(ExpectedConditions
.presenceOfElementLocated (locator);
Which exception will be thrown ?
A: Timeout NoSuchElement
Both None

26. What if?
wait = new WebDriverWait(driver,10);
driver.manage().timeouts()
.implicitlyWait(5, TimeUnit.SECONDS);

wait.until(ExpectedConditions
.presenceOfElementLocated (locator);
How long will Selenium wait ?
5 15
C: 10 25

27. What if?
wait = new WebDriverWait(driver,11);
driver.manage().timeouts()
.implicitlyWait(5, TimeUnit.SECONDS);

wait.until(ExpectedConditions
.presenceOfElementLocated (locator);
How long will Selenium wait ?
5
B: 15
11 26

28. What if?
wait = new WebDriverWait(driver,5);
driver.manage().timeouts()
.implicitlyWait(10, TimeUnit.SECONDS);

wait.until(ExpectedConditions .not(
ExpectedConditions.presenceOfElementLocated (locator));
How long will Selenium wait if element is present?
A: 5 15
10 25

29. What if?
wait = new WebDriverWait(driver,5);
driver.manage().timeouts()
.implicitlyWait(10, TimeUnit.SECONDS);

wait.until(ExpectedConditions .not(
ExpectedConditions.presenceOfElementLocated (locator));
How long will Selenium wait if element is not present?
C:
5 15
10 25

30. Coexistence rules
Use Implicit wait for element presence
Do not use Explicit wait for element presence
Always set implicit timeout lower than explicit
Timeouts must be multiple to each other
Take special care to 'not present' conditions

31. Side-by-Side comparison
Client Side (500ms)
Can wait for anything
Explicit usage
TimeoutException
Multiple network calls
Explicit Implicit
Driver Side (100ms)
Element appeared in DOM
Works automatically
NoSuchElementException
Single network call

32. Few words about Selenide
WebDriver Implicit Wait not used at all
Custom implicit waits on client side
Default polling interval - 100ms
Remote WebDriver traffic issues

33. Questions