Firefox configuration in Selenium Python - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Firefox profile configuration code?

Consider the following Selenium Python code that sets a Firefox profile preference. What will be the value of the preference browser.startup.homepage after running this code?

Selenium Python

from selenium.webdriver import Firefox
from selenium.webdriver.firefox.options import Options
from selenium.webdriver.firefox.firefox_profile import FirefoxProfile

profile = FirefoxProfile()
profile.set_preference('browser.startup.homepage', 'https://example.com')
profile.update_preferences()

options = Options()
options.profile = profile

print(profile.default_preferences.get('browser.startup.homepage'))

A https://example.com

B None

C '' (empty string)

D Raises AttributeError

💡 Hint

Check how preferences are set and accessed in FirefoxProfile.

The code sets the preference 'browser.startup.homepage' to 'https://example.com' using set_preference. Accessing it via default_preferences.get returns the set value.

❓ assertion

intermediate

Which assertion correctly verifies Firefox runs in headless mode?

Given a Selenium Firefox WebDriver instance configured to run headless, which assertion correctly checks that the browser is running in headless mode?

Selenium Python

from selenium.webdriver import Firefox
from selenium.webdriver.firefox.options import Options

options = Options()
options.headless = True

driver = Firefox(options=options)

# Which assertion below is correct?

A assert driver.options.headless == False

B assert driver.options.headless is None

C assert driver.capabilities['headless'] == 'True'

D assert driver.capabilities['moz:headless'] is True

💡 Hint

Check the capabilities dictionary for the 'moz:headless' key.

The 'moz:headless' capability is set to True when Firefox runs headless. The other options check wrong keys or values.

🔧 Debug

advanced

Why does this Firefox WebDriver fail to start with a custom profile?

This Selenium Python code tries to start Firefox with a custom profile but raises an error. Identify the cause.

Selenium Python

from selenium.webdriver import Firefox
from selenium.webdriver.firefox.options import Options
from selenium.webdriver.firefox.firefox_profile import FirefoxProfile

profile = FirefoxProfile('/path/to/custom/profile')
options = Options()
options.profile = profile

driver = Firefox(options=options)

A The profile path is invalid or inaccessible causing a FileNotFoundError

B Using options.profile with FirefoxProfile path causes an error; should use FirefoxProfile directly in Firefox()

C FirefoxProfile cannot be passed to options.profile; must use options.set_preference instead

D Missing geckodriver executable in PATH causes failure

💡 Hint

Check if the profile path exists and is accessible.

If the profile path does not exist or is inaccessible, FirefoxProfile initialization fails causing the WebDriver to fail starting.

❓ framework

advanced

How to configure Firefox to accept insecure certificates in Selenium Python?

You want Firefox WebDriver to accept insecure SSL certificates during tests. Which code snippet correctly configures this?

A

options = Options()
options.set_preference('security.insecure_field_warning.contextual.enabled', False)
driver = Firefox(options=options)

B

profile = FirefoxProfile()
profile.set_preference('acceptInsecureCerts', True)
driver = Firefox(firefox_profile=profile)

C

options = Options()
options.accept_insecure_certs = True
 driver = Firefox(options=options)

D

driver = Firefox()
driver.accept_insecure_certs = True

💡 Hint

Check the Options class for accepting insecure certs.

Setting options.accept_insecure_certs = True is the correct way to allow insecure certificates in Firefox WebDriver.

🧠 Conceptual

expert

What is the effect of setting 'dom.webnotifications.enabled' to False in Firefox profile?

In Firefox profile preferences, what does setting dom.webnotifications.enabled to False do during automated testing?

A Blocks all JavaScript execution on the page

B Disables web push notifications, preventing pop-ups during tests

C Enables web notifications, allowing tests to receive alerts

D Causes Firefox to run in safe mode

💡 Hint

Think about how notifications affect test stability.

Setting 'dom.webnotifications.enabled' to False disables web push notifications, which can interfere with automated tests by causing unexpected pop-ups.