Handle unexpected alert on form submission

Preconditions (2)

Step 1: Enter 'testuser' in the username input field

Step 2: Click the submit button

Step 3: If an alert appears, accept the alert

Step 4: Verify the page URL changes to 'https://example.com/form-success'

✅ Expected Result: The alert is accepted without causing test failure and the page navigates to the success URL

Automation Requirements - Selenium with Python

Assertions Needed:

Verify alert is present and accepted

Verify current URL is 'https://example.com/form-success'

Best Practices:

Use explicit waits to detect alert presence

Use try-except block to handle NoAlertPresentException

Avoid hardcoded sleeps

Use By.ID locator strategy for elements

Automated Solution

Selenium Python

from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
from selenium.common.exceptions import NoAlertPresentException, TimeoutException

# Setup WebDriver (assumes chromedriver is in PATH)
driver = webdriver.Chrome()

try:
    driver.get('https://example.com/form')

    # Enter username
    username_input = WebDriverWait(driver, 10).until(
        EC.presence_of_element_located((By.ID, 'username'))
    )
    username_input.send_keys('testuser')

    # Click submit button
    submit_button = driver.find_element(By.ID, 'submit-btn')
    submit_button.click()

    # Wait for alert and accept it if present
    try:
        WebDriverWait(driver, 5).until(EC.alert_is_present())
        alert = driver.switch_to.alert
        alert.accept()
    except TimeoutException:
        # No alert appeared, continue
        pass

    # Verify URL changed to success page
    WebDriverWait(driver, 10).until(
        EC.url_to_be('https://example.com/form-success')
    )
    assert driver.current_url == 'https://example.com/form-success', f"Expected URL to be 'https://example.com/form-success' but got {driver.current_url}"

finally:
    driver.quit()

This script opens the form page and waits for the username input to appear before typing 'testuser'. It then clicks the submit button. After clicking, it waits up to 5 seconds for an alert to appear. If the alert appears, it accepts it to prevent the test from failing due to unhandled alert. If no alert appears, it continues without error. Finally, it waits for the URL to change to the success page and asserts this change. The use of explicit waits ensures the script waits only as long as needed, avoiding fixed delays. The try-except block for alert handling prevents test failure if no alert is present.

Common Mistakes - 3 Pitfalls

Not handling alerts causing test to fail

Using time.sleep instead of explicit waits

Hardcoding XPath locators for common elements

Bonus Challenge

Now add data-driven testing with 3 different usernames to verify alert handling for each input

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