Firefox configuration in Selenium Python - Build an Automation Script

Configure Firefox browser to disable notifications and set custom download directory

Preconditions (2)

Step 1: Create a Firefox profile

Step 2: Set the profile preference to disable browser notifications

Step 3: Set the profile preference to automatically download files to a custom directory without prompt

Step 4: Launch Firefox browser with the configured profile

Step 5: Navigate to a test page that triggers a notification or file download

Step 6: Verify that notifications are disabled and files download automatically to the specified directory

✅ Expected Result: Firefox browser launches with notifications disabled and files download automatically to the custom directory without any prompt

Automation Requirements - Selenium with Python

Assertions Needed:

Verify Firefox browser is launched with the custom profile

Verify that browser notifications are disabled (no notification popup appears)

Verify that files download automatically to the specified directory

Best Practices:

Use FirefoxProfile to set preferences

Use explicit waits if needed

Use clear and maintainable locators

Handle browser setup and teardown properly

Automated Solution

Selenium Python

from selenium import webdriver
from selenium.webdriver.firefox.options import Options
import os
import time

def test_firefox_configuration():
    # Set custom download directory
    download_dir = os.path.join(os.getcwd(), "downloads")
    if not os.path.exists(download_dir):
        os.makedirs(download_dir)

    # Create Firefox profile and set preferences
    profile = webdriver.FirefoxProfile()
    # Disable notifications
    profile.set_preference("dom.webnotifications.enabled", False)
    # Set download directory
    profile.set_preference("browser.download.folderList", 2)  # 2 means use custom location
    profile.set_preference("browser.download.dir", download_dir)
    # Disable download prompt for common file types
    profile.set_preference("browser.helperApps.neverAsk.saveToDisk", "application/pdf,application/octet-stream")
    profile.set_preference("pdfjs.disabled", True)  # Disable built-in PDF viewer

    # Initialize Firefox options
    options = Options()
    options.profile = profile

    # Launch Firefox with profile
    driver = webdriver.Firefox(options=options)

    try:
        # Navigate to a test page that triggers download
        driver.get("https://file-examples.com/index.php/sample-documents-download/sample-pdf-download/")

        # Click the download button for a sample PDF file
        download_button = driver.find_element("xpath", "//a[contains(text(),'Download sample pdf file')]" )
        download_button.click()

        # Wait for download to complete (simple wait for demo purposes)
        time.sleep(5)

        # Verify file downloaded
        files = os.listdir(download_dir)
        assert any(file.endswith(".pdf") for file in files), "PDF file was not downloaded"

        # Since notifications are disabled, no popup should appear (cannot assert popup absence easily)
        # We rely on preference set and no exceptions thrown

    finally:
        driver.quit()

if __name__ == "__main__":
    test_firefox_configuration()

This script creates a Firefox profile with preferences to disable notifications and set a custom download directory. It disables the notification popups by setting dom.webnotifications.enabled to False. It sets the download folder to a local downloads directory and disables the download prompt for PDF files by setting browser.helperApps.neverAsk.saveToDisk. The built-in PDF viewer is disabled to force download.

The test navigates to a sample PDF download page and clicks the download link. It waits briefly to allow the file to download, then checks the download folder for a PDF file. The test asserts that the file exists, confirming the download worked automatically.

Finally, the browser is closed properly in a finally block to ensure cleanup.

Common Mistakes - 4 Pitfalls

{'mistake': 'Not setting the download directory preference correctly', 'why_bad': 'The browser will prompt for download location every time, breaking automation flow', 'correct_approach': "Set 'browser.download.folderList' to 2 and 'browser.download.dir' to the desired path"}

{'mistake': 'Not disabling notifications properly', 'why_bad': 'Notification popups can block test execution and cause flaky tests', 'correct_approach': "Set 'dom.webnotifications.enabled' preference to False in Firefox profile"}

Using hardcoded sleep instead of explicit waits

Not cleaning up downloaded files after test

Bonus Challenge

Now add data-driven testing with 3 different file types to download (PDF, CSV, XLS)

Show Hint

Practice

1. What is the main purpose of using FirefoxOptions() in Selenium tests?

easy

A. To configure Firefox browser settings before starting the test

B. To write test assertions for Firefox browser

C. To locate elements on a Firefox webpage

D. To generate test reports for Firefox tests

Solution

1. Step 1: Understand the role of FirefoxOptions

   FirefoxOptions() is used to set browser preferences like headless mode or disable notifications before launching Firefox.

2. Step 2: Differentiate from other Selenium tasks

   Locating elements, assertions, and reports are separate tasks not handled by FirefoxOptions().

3. Final Answer:

   To configure Firefox browser settings before starting the test -> Option A

4. Quick Check:

   FirefoxOptions() = configure browser [OK]

Hint: Options set browser behavior before test starts [OK]

Common Mistakes:

• Confusing options with element locators
• Thinking options generate reports
• Mixing options with assertions

2. Which of the following is the correct way to enable headless mode in Firefox using Selenium Python?

easy

A. options = FirefoxOptions()
options.set_headless(True)

B. options = FirefoxOptions()
options.add_argument('--headless')

C. options = FirefoxOptions()
options.headless = True

D. options = FirefoxOptions()
options.enable_headless()

Solution

1. Step 1: Recall correct syntax for headless mode

   In Selenium Python, options.headless = True is the standard way to enable headless mode for Firefox.

2. Step 2: Check other options for correctness

   set_headless() and enable_headless() are not valid methods. add_argument('--headless') works for Chrome but not recommended for Firefox.

3. Final Answer:

   options = FirefoxOptions() options.headless = True -> Option C

4. Quick Check:

   Set options.headless = True for Firefox headless [OK]

Hint: Use options.headless = True for Firefox headless mode [OK]

Common Mistakes:

• Using Chrome syntax like add_argument('--headless')
• Calling non-existent methods like set_headless()
• Forgetting to create FirefoxOptions instance

3. What will be the output of the following code snippet?

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

options = Options()
options.headless = True
browser = Firefox(options=options)
print(browser.capabilities['moz:headless'])
browser.quit()

medium

A. KeyError exception

B. True

C. None

D. False

Solution

1. Step 1: Understand headless option effect on capabilities

   Setting options.headless = True tells Firefox to run without UI, reflected in capabilities under key 'moz:headless' as True.

2. Step 2: Check the print statement output

   The print statement accesses browser.capabilities['moz:headless'], which will be True because headless mode is enabled.

3. Final Answer:

   True -> Option B

4. Quick Check:

   Headless mode enabled means moz:headless = True [OK]

Hint: Check capabilities key 'moz:headless' for headless status [OK]

Common Mistakes:

• Assuming 'moz:headless' key is missing
• Expecting False when headless is set True
• Confusing capabilities with options

4. Identify the error in the following Firefox configuration code and select the fix:

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

options = Options()
options.headless(True)
browser = Firefox(options=options)
browser.quit()

medium

A. Change options.headless(True) to options.headless = True

B. Import FirefoxOptions instead of Options

C. Add browser.quit() before creating browser

D. Remove options argument from Firefox() constructor

Solution

1. Step 1: Identify incorrect method call

   The line options.headless(True) incorrectly calls headless as a method, but it is a property to set.

2. Step 2: Correct syntax for setting headless

   It should be options.headless = True to enable headless mode properly.

3. Final Answer:

   Change options.headless(True) to options.headless = True -> Option A

4. Quick Check:

   Set headless as property, not method [OK]

Hint: Use assignment (=), not function call, for headless [OK]

Common Mistakes:

• Calling headless as a method
• Confusing Options class import
• Misplacing browser.quit() call

5. You want to disable Firefox notifications during Selenium tests to avoid pop-ups. Which code snippet correctly sets this preference using FirefoxOptions?

hard

A. options = FirefoxOptions()
options.set_capability('notifications', False)

B. options = FirefoxOptions()
options.add_argument('--disable-notifications')

C. options = FirefoxOptions()
options.headless = False
options.disable_notifications = True

D. options = FirefoxOptions()
options.set_preference('dom.webnotifications.enabled', False)

Solution

1. Step 1: Identify correct method to set Firefox preferences

   Use options.set_preference() to set Firefox-specific preferences like disabling notifications.

2. Step 2: Verify preference key and value

   The key 'dom.webnotifications.enabled' controls notifications; setting it to False disables them.

3. Final Answer:

   options = FirefoxOptions() options.set_preference('dom.webnotifications.enabled', False) -> Option D

4. Quick Check:

   Use set_preference with correct key to disable notifications [OK]

Hint: Use set_preference('dom.webnotifications.enabled', False) [OK]

Common Mistakes:

• Using add_argument for Firefox preferences
• Setting non-existent properties like disable_notifications
• Confusing capabilities with preferences