Headless browser execution in Selenium Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a headless Chrome browser instance.

Selenium Python

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

options = Options()
options.add_argument([1])
driver = webdriver.Chrome(options=options)
driver.get('https://example.com')
driver.quit()

Drag options to blanks, or click blank then click option'

A"--headless"

B"--disable-gpu"

C"--start-maximized"

D"--incognito"

Attempts:

3 left

💡 Hint

Common Mistakes

Using arguments unrelated to headless mode like "--disable-gpu" or "--incognito".

Not adding any argument and expecting headless mode.

Adding the "--headless" argument tells Chrome to run without opening a visible window.

2fill in blank

medium

Complete the code to set up Firefox in headless mode using Selenium.

Selenium Python

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

options = Options()
options.[1] = True
driver = webdriver.Firefox(options=options)
driver.get('https://example.com')
driver.quit()

Drag options to blanks, or click blank then click option'

Afullscreen

Bheadless

Cincognito

Dmaximize_window

Attempts:

3 left

💡 Hint

Common Mistakes

Using unrelated properties like 'fullscreen' or 'incognito'.

Setting the property to a string instead of a boolean.

Setting options.headless = True enables Firefox to run without a GUI.

3fill in blank

hard

Fix the error in the code to correctly run Chrome in headless mode.

Selenium Python

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

options = Options()
options.add_argument([1])
driver = webdriver.Chrome(options=options)
driver.get('https://example.com')
driver.quit()

Drag options to blanks, or click blank then click option'

A"--start-maximized"

B"--disable-extensions"

C"--headless"

D"--incognito"

Attempts:

3 left

💡 Hint

Common Mistakes

Not passing options to webdriver.Chrome() causes headless mode to be ignored.

Using wrong arguments that don't enable headless mode.

The code misses passing the options to Chrome driver. Adding the headless argument is correct, but options must be passed to webdriver.Chrome(options=options).

4fill in blank

hard

Fill both blanks to create a headless Chrome driver with disabled GPU.

Selenium Python

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

options = Options()
options.add_argument([1])
options.add_argument([2])
driver = webdriver.Chrome(options=options)
driver.get('https://example.com')
driver.quit()

Drag options to blanks, or click blank then click option'

A"--headless"

B"--disable-gpu"

C"--start-maximized"

D"--incognito"

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to disable GPU can cause rendering problems in headless mode.

Using unrelated arguments like "--incognito".

Headless mode requires "--headless" argument. Disabling GPU with "--disable-gpu" helps avoid some rendering issues in headless mode.

5fill in blank

hard

Fill all three blanks to create a Firefox headless driver, navigate to a page, and quit.

Selenium Python

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

options = Options()
options.[1] = True
driver = webdriver.Firefox(options=options)
driver.get([2])
driver.[3]()

Drag options to blanks, or click blank then click option'

Aheadless

B"https://example.com"

Cquit

Dmaximize_window

Attempts:

3 left

💡 Hint

Common Mistakes

Not setting headless to True causes the browser to open visibly.

Using incorrect method to close the browser like 'close' instead of 'quit'.

Passing URL without quotes causes syntax errors.

Set options.headless = True to run Firefox headless, navigate to the URL string, then call driver.quit() to close the browser.

Practice

1. What is the main advantage of running Selenium tests in headless mode?

easy

A. It requires more system resources than normal mode

B. It allows manual interaction with the browser during tests

C. Tests run faster without opening a visible browser window

D. It disables all JavaScript on the web page

Solution

1. Step 1: Understand headless mode purpose

   Headless mode runs browser tests without showing the browser window, saving time and resources.

2. Step 2: Compare options

   Only Tests run faster without opening a visible browser window correctly states that tests run faster without opening a visible window. Other options are incorrect or unrelated.

3. Final Answer:

   Tests run faster without opening a visible browser window -> Option C

4. Quick Check:

   Headless mode = faster tests without UI [OK]

Hint: Headless means no browser window visible during tests [OK]

Common Mistakes:

• Thinking headless disables JavaScript
• Assuming headless mode allows manual browser control
• Believing headless uses more resources

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

easy

A. options = webdriver.ChromeOptions()
options.add_argument('--headless')
driver = webdriver.Chrome(options=options)

B. driver = webdriver.Chrome(headless=True)

C. options = webdriver.ChromeOptions()
options.headless = True
driver = webdriver.Chrome(options=options)

D. driver = webdriver.Chrome()
driver.set_headless(True)

Solution

1. Step 1: Review Selenium headless syntax

   To enable headless mode, you add the '--headless' argument to ChromeOptions and pass it to the driver.

2. Step 2: Analyze options

   options = webdriver.ChromeOptions() options.add_argument('--headless') driver = webdriver.Chrome(options=options) correctly uses options.add_argument('--headless') and passes options to Chrome. options = webdriver.ChromeOptions() options.headless = True driver = webdriver.Chrome(options=options) incorrectly sets options.headless (not standard). Options B and D use invalid syntax.

3. Final Answer:

   options = webdriver.ChromeOptions() options.add_argument('--headless') driver = webdriver.Chrome(options=options) -> Option A

4. Quick Check:

   Use add_argument('--headless') to enable headless [OK]

Hint: Use add_argument('--headless') on ChromeOptions [OK]

Common Mistakes:

• Setting options.headless = True (not standard)
• Passing headless=True directly to webdriver.Chrome()
• Calling non-existent set_headless method

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

from selenium import webdriver
options = webdriver.ChromeOptions()
options.add_argument('--headless')
driver = webdriver.Chrome(options=options)
driver.get('https://example.com')
print(driver.title)
driver.quit()

medium

A. Opens a visible browser window and prints the title

B. Raises an error because headless mode cannot get page title

C. Prints an empty string because page is not loaded in headless mode

D. Prints the title of the page 'Example Domain' without opening a browser window

Solution

1. Step 1: Understand headless execution effect

   Headless mode runs browser without UI but fully loads pages and executes scripts.

2. Step 2: Analyze code behavior

   The code loads 'https://example.com' and prints the page title. Headless mode does not prevent getting the title, so it prints 'Example Domain'.

3. Final Answer:

   Prints the title of the page 'Example Domain' without opening a browser window -> Option D

4. Quick Check:

   Headless loads page and gets title correctly [OK]

Hint: Headless runs full browser without UI, so title is accessible [OK]

Common Mistakes:

• Assuming headless mode blocks page loading
• Expecting errors when accessing page title in headless
• Thinking headless opens visible browser window

4. You wrote this code to run Chrome in headless mode but the browser window still appears. What is the likely mistake?

from selenium import webdriver
options = webdriver.ChromeOptions()
driver = webdriver.Chrome(options=options)
options.add_argument('--headless')
driver.get('https://example.com')

medium

A. Headless mode is not supported on Chrome

B. The headless argument was added after creating the driver, so it was ignored

C. You must call driver.set_headless(True) after creating the driver

D. You forgot to call driver.quit() to close the window

Solution

1. Step 1: Check order of setting options

   The headless argument must be added to options before creating the driver instance.

2. Step 2: Identify mistake in code

   Here, options.add_argument('--headless') is called after driver creation, so the driver does not run headless.

3. Final Answer:

   The headless argument was added after creating the driver, so it was ignored -> Option B

4. Quick Check:

   Add headless argument before driver creation [OK]

Hint: Add headless option before creating driver instance [OK]

Common Mistakes:

• Adding headless argument after driver creation
• Calling non-existent set_headless method
• Assuming headless unsupported on Chrome

5. You want to run Selenium tests in headless mode on a Linux server without a display. Which combination of steps is correct to ensure tests run smoothly?

hard

A. Use ChromeOptions with '--headless' argument and set '--no-sandbox' and '--disable-dev-shm-usage' arguments

B. Use FirefoxOptions with '--headless' and run tests without any additional arguments

C. Run Chrome without headless mode but use Xvfb to simulate display

D. Use ChromeOptions with '--headless' only; no other arguments needed

Solution

1. Step 1: Understand Linux server constraints

   Linux servers often lack GUI and have limited shared memory, so Chrome needs extra flags to run headless smoothly.

2. Step 2: Identify required ChromeOptions

   Adding '--no-sandbox' and '--disable-dev-shm-usage' helps avoid permission and memory issues on Linux servers.

3. Step 3: Evaluate options

   Use ChromeOptions with '--headless' argument and set '--no-sandbox' and '--disable-dev-shm-usage' arguments correctly includes these flags with '--headless'. Use FirefoxOptions with '--headless' and run tests without any additional arguments misses Linux-specific flags. Run Chrome without headless mode but use Xvfb to simulate display uses Xvfb but not headless mode. Use ChromeOptions with '--headless' only; no other arguments needed misses important flags.

4. Final Answer:

   Use ChromeOptions with '--headless' argument and set '--no-sandbox' and '--disable-dev-shm-usage' arguments -> Option A

5. Quick Check:

   Linux headless Chrome needs extra flags for stability [OK]

Hint: Add '--no-sandbox' and '--disable-dev-shm-usage' on Linux [OK]

Common Mistakes:

• Using headless without Linux-specific flags
• Assuming Firefox needs no extra setup
• Relying on Xvfb instead of headless mode