Docker-based Grid in Selenium Python - Build an Automation Script

Run Selenium test on Docker-based Selenium Grid

Preconditions (3)

Step 1: Write a Selenium test script that connects to the Selenium Grid hub URL

Step 2: Configure the test to use Chrome browser capabilities

Step 3: Navigate to 'https://example.com' in the test

Step 4: Verify the page title is 'Example Domain'

Step 5: Close the browser session

✅ Expected Result: The test connects to the Docker Selenium Grid, runs on the Chrome node, navigates to the page, verifies the title, and finishes without errors.

Automation Requirements - Selenium with Python

Assertions Needed:

Assert page title equals 'Example Domain'

Best Practices:

Use Remote WebDriver to connect to Selenium Grid hub

Use explicit waits if needed

Use proper capabilities for browser selection

Close the driver session after test

Automated Solution

Selenium Python

from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.chrome.options import Options
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

# Selenium Grid hub URL (adjust if needed)
hub_url = 'http://localhost:4444/wd/hub'

# Set Chrome options
chrome_options = Options()

# Create Remote WebDriver instance
with webdriver.Remote(
    command_executor=hub_url,
    options=chrome_options
) as driver:
    # Navigate to the test page
    driver.get('https://example.com')

    # Wait until title is present and verify it
    WebDriverWait(driver, 10).until(EC.title_is('Example Domain'))
    assert driver.title == 'Example Domain', f"Expected title 'Example Domain' but got '{driver.title}'"

    # Driver will quit automatically due to 'with' context

The code uses Selenium's Remote WebDriver to connect to the Selenium Grid hub running in Docker at http://localhost:4444/wd/hub. We set Chrome options to specify the browser type.

The test navigates to https://example.com and waits explicitly until the page title is exactly 'Example Domain'. This ensures the page loaded correctly before asserting.

The assertion checks the page title matches the expected value. Using a with block ensures the browser session closes automatically after the test, which is a good practice to avoid leftover sessions.

Common Mistakes - 4 Pitfalls

Using local WebDriver instead of Remote WebDriver

Hardcoding browser capabilities incorrectly or missing them

Not waiting for page elements or title before asserting

Not closing the WebDriver session after test

Bonus Challenge

Now add data-driven testing to run the same test on three different URLs with their expected titles.

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