Headless mode for CI in Selenium Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Selenium headless mode setup code?

Consider this Python Selenium code snippet that sets up a Chrome browser in headless mode for CI testing. What will be printed after running this code?

Selenium Python

from selenium import webdriver
from selenium.webdriver.chrome.options import Options

options = Options()
options.add_argument('--headless')
options.add_argument('--disable-gpu')

try:
    driver = webdriver.Chrome(options=options)
    driver.get('https://example.com')
    title = driver.title
    print(title)
    driver.quit()
except Exception as e:
    print(f'Error: {e}')

A Error: Message: 'chromedriver' executable needs to be in PATH

B No output (empty string)

C Error: WebDriverException: unknown error: Chrome failed to start

D Example Domain

💡 Hint

Headless mode runs Chrome without opening a window but still loads the page and its title.

The code sets Chrome to headless mode and navigates to example.com. The page title is 'Example Domain'. If ChromeDriver is correctly installed and in PATH, the title prints successfully.

❓ assertion

intermediate

Which assertion correctly verifies the page title in headless mode?

You want to assert that the page title is exactly 'Example Domain' after loading the page in headless mode. Which assertion statement is correct?

Selenium Python

from selenium import webdriver
from selenium.webdriver.chrome.options import Options

options = Options()
options.add_argument('--headless')
driver = webdriver.Chrome(options=options)
driver.get('https://example.com')
title = driver.title

# Which assertion below is correct?

A assert 'Example' in title and 'Domain' not in title

B assert title != 'Example Domain'

C assert title == 'Example Domain'

D assert title == 'example domain'

💡 Hint

The page title is case sensitive and exactly 'Example Domain'.

The correct assertion checks that the title equals 'Example Domain' exactly. Other options either negate or mismatch the title.

🔧 Debug

advanced

Why does this headless Chrome test fail with a WebDriverException?

This Selenium Python code runs in CI but fails with the error: 'unknown error: Chrome failed to start'. What is the most likely cause?

Selenium Python

from selenium import webdriver
from selenium.webdriver.chrome.options import Options

options = Options()
options.add_argument('--headless')
# Missing this option causes failure in some CI environments
# options.add_argument('--no-sandbox')

driver = webdriver.Chrome(options=options)
driver.get('https://example.com')
print(driver.title)
driver.quit()

A The URL 'https://example.com' is unreachable in headless mode

B Missing '--no-sandbox' argument causes Chrome to fail in restricted CI environments

C The ChromeDriver version is incompatible with Chrome browser

D Headless mode is not supported on Linux

💡 Hint

Some CI environments restrict sandboxing, requiring a special Chrome option.

In many CI systems, Chrome must run with '--no-sandbox' to avoid startup failure. Without it, Chrome cannot start in headless mode.

❓ locator

advanced

Which locator strategy is best for stable element selection in headless CI tests?

You want to select a button with text 'Submit' in a page tested in headless mode. Which locator is most reliable for CI tests?

A driver.find_element('xpath', "//button[text()='Submit']")

B driver.find_element('id', 'submit')

C driver.find_element('css selector', 'button.submit-btn')

D driver.find_element('class name', 'btn')

💡 Hint

Text-based XPath is precise if the button text is unique and stable.

XPath with exact button text is less likely to break if classes or IDs change. Other locators may be less specific or unstable.

❓ framework

expert

Which CI pipeline step correctly runs Selenium tests in headless mode with Chrome on Linux?

You configure a CI pipeline to run Selenium Python tests with headless Chrome on a Linux runner. Which step setup is correct?

A Install Chrome and ChromeDriver, run tests with Chrome options '--headless', '--no-sandbox', '--disable-dev-shm-usage'

B Run tests without installing Chrome, rely on default browser, use '--headless' only

C Run tests with GUI enabled, no headless options, and use Xvfb for virtual display

D Install Firefox and use Selenium with Firefox headless mode instead of Chrome

💡 Hint

Linux CI runners often require special Chrome options and explicit installation.

For stable headless Chrome tests in Linux CI, install Chrome and ChromeDriver, and use '--headless', '--no-sandbox', and '--disable-dev-shm-usage' to avoid resource and sandbox issues.