File download handling in Selenium Python - Test Execution Trace

Test Overview

This test automates downloading a file from a web page and verifies that the file is saved correctly in the specified download folder.

Test Code - Selenium

Selenium Python

import os
import time
from selenium import webdriver
from selenium.webdriver.chrome.options import Options
from selenium.webdriver.common.by import By

# Setup Chrome options to set download directory
download_dir = os.path.join(os.getcwd(), "downloads")
if not os.path.exists(download_dir):
    os.makedirs(download_dir)

chrome_options = Options()
chrome_options.add_experimental_option("prefs", {
    "download.default_directory": download_dir,
    "download.prompt_for_download": False,
    "download.directory_upgrade": True,
    "safebrowsing.enabled": True
})

driver = webdriver.Chrome(options=chrome_options)

try:
    driver.get("https://www.selenium.dev/documentation/webdriver/browser/downloads/")

    # Find the download link for a sample file
    download_link = driver.find_element(By.LINK_TEXT, "sampleFile.txt")
    download_link.click()

    # Wait for the file to appear in the download directory
    file_path = os.path.join(download_dir, "sampleFile.txt")
    timeout = 15
    start_time = time.time()
    while not os.path.exists(file_path):
        time.sleep(1)
        if time.time() - start_time > timeout:
            break

    # Assert the file exists
    assert os.path.exists(file_path), "File was not downloaded successfully"

finally:
    driver.quit()

Execution Trace - 7 Steps

Step	Action	System State	Assertion	Result
1	Test starts and Chrome browser opens with download directory set	Chrome browser window is open with download preferences set to custom folder	—	PASS
2	Browser navigates to the Selenium downloads documentation page	Page loaded showing Selenium documentation with download links	—	PASS
3	Finds the link with text 'sampleFile.txt' on the page	Download link element is located	Element with link text 'sampleFile.txt' is found	PASS
4	Clicks the download link to start file download	Browser initiates file download to the specified folder	—	PASS
5	Waits up to 15 seconds for the file 'sampleFile.txt' to appear in download folder	File appears in the download folder within timeout	File exists at expected path	PASS
6	Asserts that the downloaded file exists	File is confirmed present in the download folder	assert os.path.exists(file_path) passes	PASS
7	Browser closes and test ends	Browser window closed, resources cleaned up	—	PASS

Failure Scenario

Failing Condition: File does not appear in the download folder within the timeout period

Execution Trace Quiz - 3 Questions

What does the test verify after clicking the download link?

A That an alert pops up

B That the page URL changes

C That the file appears in the download folder

D That the browser refreshes

Key Result

Always configure the browser to download files automatically to a known folder and verify the file presence after download to ensure the download functionality works correctly.

Practice

1. What is the main purpose of setting browser preferences in Selenium for file downloads?

easy

A. To specify the folder where downloaded files are saved automatically

B. To speed up the browser loading time

C. To change the browser's theme

D. To disable JavaScript on the page

Solution

1. Step 1: Understand browser preferences role

   Browser preferences let you control how downloads behave, like where files save.

2. Step 2: Identify the correct purpose

   Setting preferences to specify download folder avoids manual prompts and saves files automatically.

3. Final Answer:

   To specify the folder where downloaded files are saved automatically -> Option A

4. Quick Check:

   Download folder control = A [OK]

Hint: Remember: preferences set download folder and disable prompts [OK]

Common Mistakes:

• Thinking preferences speed up browser loading
• Confusing download folder with browser theme
• Assuming preferences disable JavaScript

2. Which of the following is the correct way to set Firefox preferences in Selenium to automatically download PDF files to a folder without prompt?

easy

A. profile.set_preference('browser.download.folderList', '2')

B. profile.set_preference('browser.download.folderList', 2)

C. profile.set_preference('browser.download.folderList', True)

D. profile.set_preference('browser.download.folderList', None)

Solution

1. Step 1: Recall Firefox preference for download folder

   The 'browser.download.folderList' preference expects an integer: 0 (desktop), 1 (default), 2 (custom folder).

2. Step 2: Choose correct data type and value

   Using integer 2 sets a custom folder; string or other types cause errors.

3. Final Answer:

   profile.set_preference('browser.download.folderList', 2) -> Option B

4. Quick Check:

   Integer 2 for custom folder = B [OK]

Hint: Use integer 2, not string, for custom download folder [OK]

Common Mistakes:

• Passing '2' as string instead of integer
• Using boolean True instead of integer
• Passing None which disables setting

3. Given this Selenium Python code snippet, what will be the output if the file is downloaded successfully?

import os
from selenium import webdriver

options = webdriver.FirefoxOptions()
profile = webdriver.FirefoxProfile()
profile.set_preference('browser.download.folderList', 2)
profile.set_preference('browser.download.dir', '/tmp/downloads')
profile.set_preference('browser.helperApps.neverAsk.saveToDisk', 'application/pdf')
driver = webdriver.Firefox(firefox_profile=profile, options=options)
driver.get('http://example.com/sample.pdf')

file_path = '/tmp/downloads/sample.pdf'
print(os.path.exists(file_path))

medium

A. True

B. False

C. SyntaxError

D. FileNotFoundError

Solution

1. Step 1: Analyze download setup

   Preferences set to save PDF automatically to '/tmp/downloads'.

2. Step 2: Check file existence print

   After download, os.path.exists returns True if file is present.

3. Final Answer:

   True -> Option A

4. Quick Check:

   File exists after download = True [OK]

Hint: os.path.exists returns True if file is saved correctly [OK]

Common Mistakes:

• Assuming print outputs file path string
• Expecting False without download
• Confusing syntax or runtime errors

4. Identify the error in this Selenium Python code for downloading a CSV file:

profile = webdriver.FirefoxProfile()
profile.set_preference('browser.download.folderList', 2)
profile.set_preference('browser.download.dir', '/tmp/downloads')
profile.set_preference('browser.helperApps.neverAsk.saveToDisk', 'text/csv')
driver = webdriver.Firefox(profile)
driver.get('http://example.com/data.csv')

medium

A. Missing options parameter in webdriver.Firefox()

B. Download folder path must be absolute

C. Incorrect argument name; should be firefox_profile=profile

D. Wrong MIME type for CSV files

Solution

1. Step 1: Check webdriver.Firefox() usage

   Firefox expects profile passed as firefox_profile=profile, not just profile.

2. Step 2: Confirm other settings

   MIME type 'text/csv' and folder path are correct; no options parameter needed here.

3. Final Answer:

   Incorrect argument name; should be firefox_profile=profile -> Option C

4. Quick Check:

   Use firefox_profile=profile argument = D [OK]

Hint: Pass profile with firefox_profile=profile keyword [OK]

Common Mistakes:

• Passing profile as positional argument
• Changing MIME type unnecessarily
• Using relative folder path

5. You want to verify that a file named 'report.xlsx' has been downloaded successfully using Selenium Python. Which approach is best to confirm the download in an automated test?

hard

A. Check the page source for the file name

B. Check the browser's download history via Selenium API

C. Wait for an alert popup confirming download

D. Use os.path.exists() to check the file in the download folder

Solution

1. Step 1: Understand Selenium's download verification limits

   Selenium cannot access browser download history or alerts for downloads.

2. Step 2: Use file system check

   Checking file existence with os.path.exists() in the download folder confirms the file saved.

3. Final Answer:

   Use os.path.exists() to check the file in the download folder -> Option D

4. Quick Check:

   File system check confirms download = A [OK]

Hint: Verify downloads by checking file presence on disk [OK]

Common Mistakes:

• Trying to read browser download history
• Waiting for non-existent alert popups
• Searching page source for downloaded file