Full page screenshot in Selenium Python - Test Execution Trace

Test Overview

This test opens a webpage and captures a full page screenshot. It verifies that the screenshot file is created successfully.

Test Code - Selenium

Selenium Python

from selenium import webdriver
from selenium.webdriver.chrome.service import Service
from selenium.webdriver.chrome.options import Options
import os
import time

def test_full_page_screenshot():
    options = Options()
    options.add_argument('--headless=new')
    service = Service()
    driver = webdriver.Chrome(service=service, options=options)
    try:
        driver.get('https://example.com')
        time.sleep(2)  # Wait for page to load fully
        screenshot_path = 'full_page_screenshot.png'
        # Selenium 4.1+ supports full page screenshot for Chrome
        driver.get_full_page_screenshot_as_file(screenshot_path)
        assert os.path.exists(screenshot_path), 'Screenshot file was not created.'
    finally:
        driver.quit()

Execution Trace - 6 Steps

Step	Action	System State	Assertion	Result
1	Test starts	Test environment initialized, ChromeDriver ready	—	PASS
2	Browser opens Chrome in headless mode	Chrome browser instance running without UI	—	PASS
3	Navigates to 'https://example.com'	Example.com homepage loaded fully	—	PASS
4	Waits 2 seconds for full page load	Page content fully rendered	—	PASS
5	Captures full page screenshot and saves as 'full_page_screenshot.png'	Screenshot file created in test folder	Check if 'full_page_screenshot.png' file exists	PASS
6	Closes browser and ends test	Browser closed, resources freed	—	PASS

Failure Scenario

Failing Condition: Screenshot file is not created due to permission issues or driver incompatibility

Execution Trace Quiz - 3 Questions

What does the test verify after taking the screenshot?

A That the browser is visible

B That the page title is correct

C That the screenshot file exists on disk

D That the URL contains 'example'

Key Result

Always verify that your test artifacts, like screenshots, are actually created to ensure your test is meaningful and reliable.

Practice

1. What is the main advantage of taking a full page screenshot in Selenium?

easy

A. It speeds up the test execution

B. It only captures the visible part of the webpage

C. It captures the entire webpage, including parts not visible on screen

D. It automatically scrolls the page during testing

Solution

1. Step 1: Understand what a full page screenshot means

   A full page screenshot captures the entire webpage, not just the visible part on the screen.

2. Step 2: Compare options with this definition

   Only It captures the entire webpage, including parts not visible on screen correctly states this advantage. Options B, C, and D describe other unrelated behaviors.

3. Final Answer:

   It captures the entire webpage, including parts not visible on screen -> Option C

4. Quick Check:

   Full page screenshot = entire page capture [OK]

Hint: Full page means entire webpage, not just visible part [OK]

Common Mistakes:

• Confusing full page with visible viewport only
• Thinking it speeds up tests automatically
• Assuming it scrolls the page during capture

2. Which Selenium Python method is used to save a full page screenshot in Firefox?

easy

A. driver.get_screenshot_as_file('file.png')

B. driver.save_full_page_screenshot('file.png')

C. driver.save_screenshot('file.png')

D. driver.take_full_screenshot('file.png')

Solution

1. Step 1: Identify the correct method for full page screenshot in Firefox

   Firefox does not have a built-in method named save_full_page_screenshot. The standard method to save a screenshot is get_screenshot_as_file, which captures the visible viewport.

2. Step 2: Check other options for correctness

   driver.save_full_page_screenshot('file.png') is invalid as save_full_page_screenshot is not a standard Selenium method. driver.save_screenshot('file.png') saves visible viewport screenshot. driver.take_full_screenshot('file.png') is not a valid method.

3. Final Answer:

   driver.get_screenshot_as_file('file.png') -> Option A

4. Quick Check:

   Standard screenshot method = get_screenshot_as_file [OK]

Hint: Use get_screenshot_as_file to save screenshot [OK]

Common Mistakes:

• Using non-existent save_full_page_screenshot method
• Confusing save_screenshot with full page capture
• Trying invalid methods like take_full_screenshot

3. Given this code snippet, what will be the result?

driver.get('https://example.com')
driver.save_full_page_screenshot('page.png')
print('Screenshot saved')

medium

A. Runtime error because get_full_page_screenshot_as_file is unsupported

B. Screenshot saved and full page screenshot saved as 'page.png'

C. Only visible part screenshot saved as 'page.png'

D. SyntaxError due to incorrect method name

Solution

1. Step 1: Analyze the method usage

   The method save_full_page_screenshot is not a valid Selenium WebDriver method and will cause a SyntaxError or AttributeError.

2. Step 2: Check the print statement

   The print statement will not execute because the previous line causes an error.

3. Final Answer:

   SyntaxError due to incorrect method name -> Option D

4. Quick Check:

   Invalid method call causes error [OK]

Hint: Invalid method names cause errors [OK]

Common Mistakes:

• Assuming method is supported causing success
• Confusing full page with visible screenshot
• Thinking method name is correct syntax

4. You wrote this code but get a blank screenshot file:

driver.get('https://example.com')
driver.save_screenshot('screen.png')

What is the likely cause?

medium

A. Page did not fully load before screenshot

B. save_screenshot does not save files

C. Method get_full_page_screenshot_as_file is required instead

D. Screenshot file path is invalid

Solution

1. Step 1: Understand why screenshot is blank

   If the page is not fully loaded, the screenshot may capture a blank or incomplete page.

2. Step 2: Evaluate other options

   save_screenshot does save files. Method get_full_page_screenshot_as_file is unrelated to blank screenshot issue. Invalid file path would cause an error, not a blank file.

3. Final Answer:

   Page did not fully load before screenshot -> Option A

4. Quick Check:

   Wait for page load before screenshot [OK]

Hint: Always wait for page load before screenshot [OK]

Common Mistakes:

• Assuming save_screenshot never saves files
• Confusing full page screenshot with blank image issue
• Ignoring page load timing problems

5. How can you ensure a clean full page screenshot in headless Firefox using Selenium Python?

hard

A. Use save_screenshot immediately after driver.get() without waits

B. Scroll manually and take multiple viewport screenshots

C. Use headless mode, wait for page load, then call save_full_page_screenshot

D. Use driver.execute_script to hide elements before screenshot

Solution

1. Step 1: Understand headless mode limitations

   Headless Firefox does not support a built-in full page screenshot method.

2. Step 2: Use manual scrolling and multiple viewport screenshots

   To capture the full page, scroll manually and stitch multiple viewport screenshots.

3. Final Answer:

   Scroll manually and take multiple viewport screenshots -> Option B

4. Quick Check:

   Manual scroll + multiple screenshots = full page capture [OK]

Hint: Manual scrolling needed for full page in headless Firefox [OK]

Common Mistakes:

• Assuming save_full_page_screenshot exists in headless mode
• Taking screenshot immediately without waiting
• Hiding elements unnecessarily before capture