How to Write and Run Selenium Scripts: Step-by-Step Guide

What is a Selenium Script & Why It Matters

A Selenium script is code written to automate interactions with a browser. It can perform tasks such as:

• Opening a website and navigating across pages.
  
• Filling out and submitting forms.
  
• Validating search results or login success.
  
• Handling popups, multiple tabs, or dynamic elements.
  

The importance of Selenium scripts lies in their ability to:

• Reduce manual effort in regression and smoke testing.
  
• Improve coverage across browsers and platforms.
• Integrate seamlessly into CI/CD pipelines for continuous testing.

Software and Driver Requirements for Executing Selenium Scripts

Before writing a Selenium script, certain prerequisites must be met:

• Programming language setup: Selenium supports Java, Python, C#, JavaScript, and Ruby. Install the language environment of your choice.‍
• Selenium WebDriver: Install the library or dependency.

Python:

pip install selenium

• Java: Add Selenium Maven dependency.‍
• Browser drivers: ChromeDriver for Chrome, GeckoDriver for Firefox, EdgeDriver for Microsoft Edge, and so on. The driver version must match the browser version.‍
• IDE setup: Tools like PyCharm, IntelliJ IDEA, or Visual Studio Code help write and debug Selenium code efficiently.

Writing the First Automation Script (Quick Start)

Here’s a minimal Selenium Python script to open Google, search for “Selenium,” and validate results:

from selenium import webdriver

from selenium.webdriver.common.by import By

# Initialize browser

driver = webdriver.Chrome()

# Open Google

driver.get("https://www.google.com")

# Search for Selenium

search_box = driver.find_element(By.NAME, "q")

search_box.send_keys("Selenium")

search_box.submit()

# Validate result

assert "Selenium" in driver.title

# Close browser

driver.quit()

This simple script demonstrates the lifecycle: setup → interaction → validation → teardown.

Deep Dive: Test Script Anatomy

Every Selenium script follows a common structure. Breaking it into components makes it easier to design and maintain tests.

Browser Session Setup

Scripts begin with initiating a browser session:

driver = webdriver.Chrome()

driver.get("https://example.com")

This launches Chrome and navigates to the target URL.

Element Locators & Actions

Locating and interacting with elements is the core of Selenium scripting. Common locator strategies include:

• By.ID
  
• By.NAME
  
• By.CSS_SELECTOR
• By.XPATH

Example:

login_button = driver.find_element(By.ID, "login")

login_button.click()

Synchronization & Waits

Web pages may load elements asynchronously. To prevent failures, waits are essential:

from selenium.webdriver.support.ui import WebDriverWait

from selenium.webdriver.support import expected_conditions as EC

WebDriverWait(driver, 10).until(

    EC.presence_of_element_located((By.ID, "dashboard"))

)

Explicit waits ensure Selenium interacts only when elements are ready.

Assertions & Validation

Assertions confirm that the script achieves its expected outcome:

assert "Dashboard" in driver.title

This ensures test reliability by validating results against expectations.

Handling Complex Scenarios

Real-world applications often present advanced challenges. Selenium provides mechanisms to handle them effectively.

Alerts, Popups, and Multiple Windows

Alerts:

alert = driver.switch_to.alert

alert.accept()

New Windows/Tabs:

driver.switch_to.window(driver.window_handles[1])

Dynamic Content & AJAX Calls

Modern applications load content dynamically. Selenium waits help handle AJAX-driven pages:

WebDriverWait(driver, 15).until(

    EC.text_to_be_present_in_element((By.ID, "status"), "Completed")

)

Data-driven Script Design

Instead of hardcoding test data, external sources (Excel, JSON, CSV, or databases) can feed scripts dynamically. This approach improves reusability and coverage.

Example (reading from a CSV in Python):

import csv

with open('testdata.csv') as file:

    reader = csv.reader(file)

    for row in reader:

        username, password = row

        # Use values in Selenium script

Best Practices for Script Maintainability

For scalable automation suites, adopt the following practices:

• Implement Page Object Model (POM) to separate locators from test logic.
  
• Use explicit waits instead of arbitrary sleep timers.
  
• Store test data externally for easy updates.
  
• Write modular scripts with reusable functions.
• Validate scripts on real browsers and devices to minimize false positives.

Why run Selenium Scripts on the Cloud 

Local testing environments often fail to capture real-world diversity of browsers, operating systems, and devices. Running Selenium scripts on real environments offers benefits such as:

• Accurate replication of user conditions.
  
• Cross-browser validation to catch compatibility issues.
  
• Device-level testing for mobile browsers.
• Scalable execution without local infrastructure maintenance.

BrowserStack Automate provides access to 3,500+ real browsers and devices. By integrating Selenium tests with Automate, teams can:

• Run tests in parallel across multiple environments.
  
• Validate on the latest and legacy browser versions.
  
• Integrate seamlessly with CI/CD pipelines like Jenkins, GitHub Actions, and Azure DevOps.
  

This ensures faster feedback cycles, improved reliability, and broader test coverage without building an in-house device lab.

Summary

Selenium scripts enable testers to automate everything from simple UI validations to complex multi-step workflows. By understanding script anatomy, handling dynamic scenarios, applying best practices, and running tests on real devices through platforms like BrowserStack Automate, teams can achieve robust, scalable, and reliable web automation.