File download handling in Selenium Python

Introduction

We handle file downloads in tests to check if files are saved correctly. This helps ensure users get the right files from the website.

When testing if a report downloads correctly from a web app.

When verifying that an invoice PDF is generated and saved.

When checking if a CSV export feature works as expected.

When automating tests that require saving images or documents from a site.

Syntax

Selenium Python

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

options = Options()
options.add_experimental_option('prefs', {
    'download.default_directory': '/path/to/download/folder',
    'download.prompt_for_download': False,
    'download.directory_upgrade': True,
    'safebrowsing.enabled': True
})
driver = webdriver.Chrome(options=options)

Set the download folder path to control where files save.

Disabling prompts lets downloads happen automatically.

Examples

This sets the download folder to '/tmp/downloads' and disables the download prompt.

Selenium Python

options.add_experimental_option('prefs', {
    'download.default_directory': '/tmp/downloads',
    'download.prompt_for_download': False
})

Clicks the button that starts the file download.

Selenium Python

driver.find_element('id', 'downloadButton').click()

Sample Program

This script sets a download folder, opens a page, clicks a download button, waits, and checks if the file is saved.

Selenium Python

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

# Set download folder path
download_folder = os.path.join(os.getcwd(), 'downloads')
os.makedirs(download_folder, exist_ok=True)

# Configure Chrome options for automatic download
options = Options()
options.add_experimental_option('prefs', {
    'download.default_directory': download_folder,
    'download.prompt_for_download': False,
    'download.directory_upgrade': True,
    'safebrowsing.enabled': True
})

driver = webdriver.Chrome(options=options)

try:
    driver.get('https://example.com/download')
    # Click the download link/button
    driver.find_element('id', 'downloadFile').click()

    # Wait for the file to download (simple wait for demo)
    time.sleep(5)

    # Check if file exists in download folder
    files = os.listdir(download_folder)
    if files:
        print(f"Download successful: {files[0]}")
    else:
        print("Download failed: No files found")
finally:
    driver.quit()

Important Notes

Always set a unique download folder per test to avoid confusion.

Use explicit waits or check file size to confirm download completion in real tests.

Adjust file name checks based on expected download file names.

Summary

Set browser preferences to control download folder and disable prompts.

Trigger downloads by clicking the right page element.

Verify downloads by checking the file system for saved files.

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