Unexpected alert handling in Selenium Java - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output when an unexpected alert appears?

Consider the following Selenium Java code snippet. What will be the output when an unexpected alert pops up during the click action?

Selenium Java

try {
    driver.findElement(By.id("submitBtn")).click();
    System.out.println("Clicked successfully");
} catch (UnhandledAlertException e) {
    System.out.println("Alert detected and handled");
}

A Alert detected and handled

B Clicked successfully

C No output, test hangs

D Throws NoSuchElementException

💡 Hint

Think about what happens when an alert blocks interaction in Selenium.

When an unexpected alert appears, Selenium throws UnhandledAlertException. The catch block prints "Alert detected and handled".

❓ assertion

intermediate

Which assertion correctly verifies alert text?

You want to verify that an alert's text is exactly "Session expired". Which assertion is correct?

Selenium Java

Alert alert = driver.switchTo().alert();
String alertText = alert.getText();

A assertEquals(alertText, "Session expired");

B assertTrue(alertText.contains("Session expired"));

C assertFalse(alertText.equals("Session expired"));

D assertNull(alertText);

💡 Hint

Exact match requires equality assertion.

assertEquals checks exact equality, which is needed here. Other options check contains, false equality, or null which are incorrect.

🔧 Debug

advanced

Why does this code fail to handle an unexpected alert?

This code tries to accept an unexpected alert but fails with UnhandledAlertException. Identify the cause.

Selenium Java

try {
    driver.findElement(By.id("saveBtn")).click();
    driver.switchTo().alert().accept();
} catch (NoAlertPresentException e) {
    System.out.println("No alert to accept");
}

A driver.findElement throws exception, not handled

B NoAlertPresentException is not caught properly

C accept() method is deprecated and causes failure

D Alert appears before click, click() throws UnhandledAlertException before switchTo().alert()

💡 Hint

Consider when the alert appears relative to the click.

If alert appears before click, the click() throws UnhandledAlertException because alert was blocking interaction. The code never reaches switchTo().alert(), and UnhandledAlertException is not caught.

❓ framework

advanced

Best practice to handle unexpected alerts in Selenium tests?

Which approach is best to handle unexpected alerts globally in Selenium Java tests?

A Ignore alerts and let tests fail to fix issues manually

B Wrap every click action in try-catch for UnhandledAlertException

C Use WebDriver event listeners to detect and accept alerts automatically

D Use Thread.sleep() before every action to wait for alerts

💡 Hint

Think about a scalable way to handle alerts without repeating code.

Event listeners allow centralized handling of alerts, improving maintainability and reducing code duplication.

🧠 Conceptual

expert

What happens if you ignore an unexpected alert in Selenium?

If a test encounters an unexpected alert and does not handle it, what is the most likely outcome?

A Test ignores alert and continues normally

B Test throws UnhandledAlertException and stops execution

C Alert automatically closes after timeout

D Test logs warning but passes

💡 Hint

Selenium blocks interaction when alert is present.

Selenium throws UnhandledAlertException when an unexpected alert blocks interaction, causing test failure unless handled.

Practice

1. What is the main reason to handle unexpected alerts in Selenium tests?

easy

A. To prevent tests from stopping abruptly due to unhandled pop-ups

B. To improve the speed of test execution

C. To change the browser window size automatically

D. To log user actions during the test

Solution

1. Step 1: Understand unexpected alerts impact

   Unexpected alerts block the browser and stop test execution if not handled.

2. Step 2: Purpose of handling alerts

   Handling alerts allows the test to continue smoothly without interruption.

3. Final Answer:

   To prevent tests from stopping abruptly due to unhandled pop-ups -> Option A

4. Quick Check:

   Unexpected alerts stop tests = Handle alerts [OK]

Hint: Handle alerts to keep tests running without interruption [OK]

Common Mistakes:

• Thinking alerts only slow tests, not stop them
• Confusing alert handling with browser resizing
• Assuming alerts are for logging only

2. Which Selenium Java code snippet correctly switches to an alert and accepts it?

easy

A. driver.switchTo().alert().dismiss();

B. driver.alert().switchTo().accept();

C. driver.switchTo().alert().accept();

D. driver.switchTo().alert().sendKeys();

Solution

1. Step 1: Identify correct alert switching syntax

   The correct method to switch to alert is driver.switchTo().alert()

2. Step 2: Accept the alert

   Calling accept() on the alert confirms it and closes the pop-up.

3. Final Answer:

   driver.switchTo().alert().accept(); -> Option C

4. Quick Check:

   Switch to alert then accept = driver.switchTo().alert().accept() [OK]

Hint: Use driver.switchTo().alert().accept() to accept alerts [OK]

Common Mistakes:

• Reversing switchTo() and alert() calls
• Using dismiss() instead of accept() when accept is needed
• Calling sendKeys() without parameters

3. What will happen if the following code runs when an unexpected alert is present?

driver.findElement(By.id("submit")).click();
driver.switchTo().alert().dismiss();
driver.findElement(By.id("next")).click();

medium

A. The alert will be accepted instead of dismissed

B. No alert handling occurs and test throws NoAlertPresentException

C. The test will fail at clicking submit due to alert presence

D. The alert will be dismissed and the next button clicked successfully

Solution

1. Step 1: Click triggers alert

   Clicking submit may cause an alert to appear unexpectedly.

2. Step 2: Alert is dismissed explicitly

   driver.switchTo().alert().dismiss() closes the alert, allowing further actions.

3. Step 3: Next element interaction

   After dismissing alert, clicking next proceeds without interruption.

4. Final Answer:

   The alert will be dismissed and the next button clicked successfully -> Option D

5. Quick Check:

   Dismiss alert then continue = success [OK]

Hint: Dismiss alert before next action to avoid test failure [OK]

Common Mistakes:

• Assuming alert auto-dismisses without code
• Expecting accept() instead of dismiss() here
• Ignoring NoAlertPresentException possibility

4. Identify the error in this code snippet handling unexpected alerts:

try {
  driver.findElement(By.id("save")).click();
} catch (NoAlertPresentException e) {
  driver.switchTo().alert().accept();
}

medium

A. NoAlertPresentException should be caught after alert handling

B. Alert handling code is inside catch for wrong exception

C. Accept() should be replaced with dismiss()

D. Try block should include alert handling, not catch

Solution

1. Step 1: Understand exception usage

   NoAlertPresentException occurs when alert is not present but code tries to switch to alert.

2. Step 2: Analyze catch block logic

   Alert handling code is wrongly placed inside catch for NoAlertPresentException, which means alert is not present.

3. Step 3: Correct approach

   Alert handling should be in try block or catch should handle different exception like UnhandledAlertException.

4. Final Answer:

   Alert handling code is inside catch for wrong exception -> Option B

5. Quick Check:

   Catch wrong exception for alert handling = error [OK]

Hint: Catch UnhandledAlertException, not NoAlertPresentException for alerts [OK]

Common Mistakes:

• Catching NoAlertPresentException to handle alert
• Placing alert.accept() inside catch for missing alert
• Confusing accept() and dismiss() usage

5. You want to write a Selenium Java method that safely clicks a button even if an unexpected alert appears. Which code snippet correctly handles this scenario?

hard

A. try {
driver.findElement(By.id("btn")).click();
} catch (UnhandledAlertException e) {
driver.switchTo().alert().accept();
driver.findElement(By.id("btn")).click();
}

B. driver.findElement(By.id("btn")).click();
driver.switchTo().alert().accept();

C. driver.switchTo().alert().accept();
driver.findElement(By.id("btn")).click();

D. try {
driver.switchTo().alert().accept();
} catch (NoAlertPresentException e) {
driver.findElement(By.id("btn")).click();
}

Solution

1. Step 1: Understand unexpected alert during click

   Clicking the button may cause an unexpected alert, throwing UnhandledAlertException.

2. Step 2: Use try-catch to handle alert and retry click

   Catch UnhandledAlertException, accept alert, then retry clicking the button to ensure action completes.

3. Step 3: Verify other options

   driver.findElement(By.id("btn")).click(); driver.switchTo().alert().accept(); and C do not handle exceptions; try { driver.switchTo().alert().accept(); } catch (NoAlertPresentException e) { driver.findElement(By.id("btn")).click(); } tries alert first which may not exist before click.

4. Final Answer:

   try { driver.findElement(By.id("btn")).click(); } catch (UnhandledAlertException e) { driver.switchTo().alert().accept(); driver.findElement(By.id("btn")).click(); } -> Option A

5. Quick Check:

   Catch alert exception, accept, retry click = safe handling [OK]

Hint: Catch alert exception, accept alert, then retry action [OK]

Common Mistakes:

• Not retrying click after alert acceptance
• Handling alert before click without exception
• Catching wrong exception types