Selenium WebDriver quiz (Java): 20 questions with explanations

Which locator is generally the most reliable, when it is present and unique?

• Absolute XPath
• Link text
• id
• Tag name

Answer: id. A unique id is fast and does not depend on layout. Absolute XPath breaks with any change to the page structure, and tag names are rarely unique.

Which XPath selects a button whose visible text is "Sign in", ignoring extra spaces around it?

• //button[normalize-space()='Sign in']
• //button[@text='Sign in']
• //button.text('Sign in')
• /button[Sign in]

Answer: //button[normalize-space()='Sign in']. text() and normalize-space() read the element's text. There is no @text attribute in HTML, and the other two are not valid XPath.

Which CSS selector matches the element with id "login"?

• .login
• login
• @login
• #login

Answer: #login. # selects by id and . selects by class. A bare word selects a tag name.

What does driver.findElements(By.className("row")) return if nothing matches?

• It throws NoSuchElementException
• An empty list
• null
• It waits for 30 seconds and then throws

Answer: An empty list. findElements returns an empty list when there is no match, which makes it useful for checking that something is absent. Only findElement throws.

Which exception does driver.findElement throw when no element matches the locator?

• NoSuchElementException
• StaleElementReferenceException
• TimeoutException
• InvalidSelectorException

Answer: NoSuchElementException. NoSuchElementException means the lookup found nothing at that moment. InvalidSelectorException means the locator syntax itself is wrong.

Which wait applies to every element lookup for the whole driver session?

• Explicit wait
• Fluent wait
• Implicit wait
• Thread.sleep

Answer: Implicit wait. An implicit wait is set once on the driver and applies to all findElement calls. Explicit and fluent waits apply to one condition at a time.

Why is Thread.sleep(5000) a poor way to wait for an element?

• It is not allowed in Java
• It only works in Chrome
• It stops the browser
• It always waits the full time and still fails if the page takes longer

Answer: It always waits the full time and still fails if the page takes longer. A fixed sleep wastes time when the page is fast and is not enough when it is slow. A condition-based wait continues as soon as the condition is true.

Which line waits up to 10 seconds for a toast message to become visible?

WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(10));

• wait.until(ExpectedConditions.alertIsPresent(By.id("toast")));
• wait.until(ExpectedConditions.visibilityOfElementLocated(By.id("toast")));
• wait.sleep(By.id("toast"));
• driver.waitFor(By.id("toast"));

Answer: wait.until(ExpectedConditions.visibilityOfElementLocated(By.id("toast")));. visibilityOfElementLocated polls until the element exists and is displayed. alertIsPresent is for browser alerts and takes no locator.

A StaleElementReferenceException usually means:

• The element you hold was removed or replaced in the page, so the reference is dead
• The locator syntax is wrong
• The browser version is too old
• The element is hidden behind another element

Answer: The element you hold was removed or replaced in the page, so the reference is dead. The WebElement points to a specific DOM node. After a re-render that node is gone even if an identical-looking one exists. Look the element up again.

How do you act on an element inside an iframe?

• Call findElement as usual; Selenium searches all frames
• Use a special XPath that starts with //iframe
• Switch to the frame with driver.switchTo().frame(...) first
• Open the iframe URL in a new window only

Answer: Switch to the frame with driver.switchTo().frame(...) first. Selenium looks only at the current browsing context. Switch into the frame, act, then switch back with defaultContent().

Which call returns the driver to the main page after working inside a frame?

• driver.switchTo().parent().top()
• driver.back()
• driver.switchTo().window()
• driver.switchTo().defaultContent()

Answer: driver.switchTo().defaultContent(). defaultContent() goes back to the top-level document. parentFrame() would go up only one level.

How do you accept a JavaScript alert?

• driver.findElement(By.tagName("alert")).click();
• driver.switchTo().alert().accept();
• driver.alert().ok();
• driver.close();

Answer: driver.switchTo().alert().accept();. Alerts are not part of the page DOM. Switch to the alert, then accept() or dismiss() it.

What is the usual way to upload a file when the page has an input of type file?

• Call sendKeys on that input with the absolute path of the file
• Click the input and type the path into the operating system dialog using Selenium
• Use the Actions class to drag the file from the desktop
• Selenium cannot upload files

Answer: Call sendKeys on that input with the absolute path of the file. Selenium cannot drive native operating system dialogs. Sending the file path to the input element sets the file directly.

Which class do you use for a native HTML select (dropdown) element?

• Dropdown
• Actions
• Select
• WebList

Answer: Select. The Select class wraps a select element and offers selectByVisibleText, selectByValue and selectByIndex. Custom dropdowns made of div elements are clicked like normal elements.

Which method moves the mouse over a menu item to reveal a sub-menu?

• driver.hover(element)
• element.hover()
• new Select(element).hover()
• new Actions(driver).moveToElement(element).perform()

Answer: new Actions(driver).moveToElement(element).perform(). Mouse hover, drag and drop and keyboard chords go through the Actions class. Remember to call perform().

What is the main benefit of the Page Object Model?

• It makes tests run faster
• Locators and page actions live in one place, so a UI change is fixed once instead of in every test
• It removes the need for waits
• It lets Selenium test mobile apps

Answer: Locators and page actions live in one place, so a UI change is fixed once instead of in every test. Page objects separate what the test does from how the page is operated. When a locator changes you edit one class. They do not speed up execution.

Which TestNG annotation runs before every test method?

• @BeforeMethod
• @BeforeClass
• @BeforeSuite
• @Test(priority = 0)

Answer: @BeforeMethod. @BeforeMethod runs before each @Test method, which is where you usually create a fresh driver. @BeforeClass runs once per class.

Tests run in parallel and share one static WebDriver field. What is the likely result?

• The tests run twice as fast with no side effects
• Selenium creates a driver per thread automatically
• Only the first test runs
• Tests interfere with each other, clicking in each other's browsers and failing randomly

Answer: Tests interfere with each other, clicking in each other's browsers and failing randomly. A WebDriver is not thread-safe. Give each thread its own driver, for example through ThreadLocal<WebDriver> or a per-test fixture.

What does driver.quit() do that driver.close() does not?

• Nothing, they are identical
• It closes only the current tab
• It ends the session, closing all windows and stopping the driver process
• It clears the browser cache

Answer: It ends the session, closing all windows and stopping the driver process. close() closes the window in focus. quit() ends the whole session. Always call quit() in teardown so driver processes do not pile up.

Which of these is new in Selenium 4?

• The findElement method
• Relative locators such as above(), below() and toRightOf()
• The WebDriver interface
• The Select class

Answer: Relative locators such as above(), below() and toRightOf(). Selenium 4 added relative locators (RelativeLocator.with(...)), driver.switchTo().newWindow(), and better access to browser DevTools. The other items have existed since Selenium 2 or 3.