Your Complete Guide to Cross Browser Testing with Selenium

As an app testing expert with over 10 years of experience across 3,500+ real devices and browsers, I‘ve seen how vital thorough cross browser testing is for providing a flawless user experience. When web apps don‘t work seamlessly across Chrome, Firefox, Safari and more, users get frustrated — and so do developers!

That‘s why smart engineering teams automate cross browser testing early and often using Selenium. In this comprehensive guide, I‘ll walk you through everything you need to know to start running automated cross browser tests with Selenium, including:

• The importance of cross browser testing: Understand why testing across browsers matters
• How to set up Selenium for browser test automation: Step-by-step instructions for configuring drivers and tests suites
• Best practices based on over a decade of experience: Tips and techniques curated from real-world results
• Sample code and scripts: Real examples illustrate techniques

I‘ll share actionable advice so you can quickly build Selenium test frameworks that catch browser issues early and improve user experiences. So let‘s get right to it!

Why Cross Browser Testing Matters

Before we dive into the Selenium setup process, let‘s briefly cover why properly testing web apps across browsers is so crucial nowadays…

Users access your sites from different browsers

Your web app visitors browse from Chrome, Firefox and Safari on both desktop and mobile devices. Each browser interprets HTML, CSS and JavaScript slightly differently thanks to disparate rendering engines:

Testing across browsers minimizes rendering differences and display issues.

Browser compatibility problems ruin experiences

Have you ever visited a website where images were broken, buttons didn‘t work or site sections were out of place?

These catastrophes happen due to browser compatibility problems. Just a little CSS or JavaScript bug can negatively impact key site functionality and completely shatter user experiences.

Proper continuous testing prevents these disastrous scenarios.

Outdated browsers still have significant market share

While Chrome, Safari and Firefox take up the bulk of the browser market worldwide, legacy browsers still represent meaningful percentages:

• Internet Explorer still has ~5% desktop browser share
• Safari makes up over 50% of mobile browsing

You want complete assurance your web apps work flawlessly across both modern and legacy browsers.

Now that you see why properly testing across browsers matters so much, let‘s look at how to leverage Selenium to automate this critical process.

Step-by-Step Selenium Setup

The first step is determining exactly which browsers and browser versions you need to test against.

Analyze your customer base and visitor demographics to create a browser test matrix. Prioritize any browsers with over 5% market share.

Once your test matrix is defined, we can use Selenium to automate tests against this multi-browser environment.

Here is an step-by-step overview of setting up Selenium for automated cross browser testing:

1. Construct Your Test Automation Framework

Since manually testing websites across different browsers is tedious and repetitive, smart teams invest time upfront to create selenium test frameworks.

These frameworks allow you to write test cases once, then easily execute them across various browsers and browser versions.

For constructing test frameworks, you will need:

• Selenium client libraries: Bindings for your language like python, Java, C#, etc.
• Browser-specific web drivers: Launch and control individual browser instances
• Test runner like TestNG: Execute full test suites across configurations

With these components wired together, you have a solid foundation for stable automated cross browser testing.

2. Configure Web Drivers For Each Browser

The cornerstone of automated browser testing is web drivers.

These drivers allow you to spawn browser instances programmatically. Selenium offers native support for all major browsers:

// Launch chrome instance
WebDriver driver = new ChromeDriver();

// Launch firefox instance
WebDriver driver = new FirefoxDriver();

// Launch edge instance
WebDriver driver = new EdgeDriver(); 

Configure a unique driver for each browser in your test matrix. Manage them together as you alternate between browsers.

3. Parameterize Test Methods

Parameterizing your test methods enables easy switching between configured web drivers.

Observe this example:

// Test class
public class CrossBrowserTests {

  // Browser parameter
  @Parameters({"browser"})

  // Initialize driver based on parameter 
  @BeforeTest 
  public void setup(String browser) {
    if(browser.equals("chrome")) {
      driver = new ChromeDriver();
    }
    // Additional logic
  }

  @Test
  public void test_crossBrowser() {
    // Shared test logic reused across browsers 
  }

}  

Now test runs can simply pass "chrome" or "firefox" to run the test_crossBrowser method against different browsers using the single shared driver instance.

This technique minimizes duplicate code when testing across multiple browsers.

4. Construct Test Suites

Finally, leverage your test runner framework to build cross browser test suites.

<!-- TestNG sample -->

<suite name="CrossBrowserSuite">

  <test name="Chrome"> 
    <classes>
       <class name="CrossBrowserTests"/>
    </classes>
  </test>

  <test name="Firefox">
    <classes>
       <class name="CrossBrowserTests"/> 
    </classes>
  </test>

</suite>

Execute the test suite to run all test methods against all configured browsers and drivers. This makes scaling cross browser test coverage easy.

Now you have a complete Selenium automation solution for catching browser issues early!

Best Practices From My Experience

Through over a decade of hands-on experience using Selenium for cross browser testing, I‘ve compiled some key best practices:

Continuously expand browser matrix

As new browser versions release, expand your test matrix accordingly. Also periodically evaluate usage stats using tools like StatCounter to add niche browsers if their adoption grows.

Stay on the cutting edge of browser updates so your test coverage reflects real-world usage.

Research browser support before choosing frameworks

Before deciding on JavaScript, CSS and HTML frameworks, thoroughly vet browser support. Some cutting-edge frameworks still have patchy legacy browser support. Double check before moving forward.

Analyze root causes of test failures

When tests fail on some browsers/versions but not others, dig into root causes instead of just adding hack fixes. Pinpoint the specific standards interpretations or rendering issues triggering the failure.

Consider leveraging expert cloud test labs

If supporting every niche browser in-house grows too complex, consider outsourcing to cloud test labs. These labs maintain thousands of real devices and browsers, making test coverage easy.

Adopt unit testing

Supplement end-to-end Selenium tests with lower-level JavaScript unit tests focused on functionality. These help further validate cross browser compatibility early.

Now let‘s look at real-world examples of cross browser Selenium scripts in action…

Real-World Selenium Scripts

Hopefully these concepts make practical sense. Now I want to share some real-world Selenium test examples to solidify these techniques.

Let‘s walk through a sample Selenium test class to showcase parameterizing tests for easily swapping browser configurations:

// Imports
import org.testng.annotations.Parameters;
import org.testng.annotations.Test;

public class CrossBrowserTest {

  // Browser parameter 
  @Parameters({"browser"}) 
  WebDriver driver; 

  @BeforeTest
  public void setup(String browser) {
    // Initialize driver
    if(browser.equals("chrome")) {
      // Init chrome driver
    } else if(browser.equals("firefox")) {
      // Init firefox driver
    }
  }

  @Test
  public void validateHeaders() {
    // Shared test logic to validate headers
    Assert.assertEquals(driver.getPageSource().contains("<h1>"), true);    
  }

  @AfterTest 
  public void cleanUp() {
    driver.close();
  }

}

And sample TestNG test suite:

<?xml version="1.0" encoding="UTF-8"?>
<suite name="CrossBrowserSuite">

  <test name="Chrome">
    <parameter name="browser" value="chrome"/>
    <classes>
      <class name="CrossBrowserTest"/>
    </classes>  
  </test>

  <test name="Firefox">
    <parameter name="browser" value="firefox"/> 
    <classes>
      <class name="CrossBrowserTest"/>
    </classes>
  </test>

</suite>

This setup allows running the validateHeaders test easily across different browsers just by passing browser parameter values. Straightforward!

Let me know in the comments if you have any other Selenium cross browser testing questions!

Go Forth and Test Across Browsers

I hope this guide gives you a solid foundation for setting up robust automated cross browser testing processes with Selenium.

As you saw, the keys are:

✅Parameterizing tests to enable easy browser configuration swapping
✅Constructing cross browser test groups/suites
✅Configuring unique web drivers for each browser
✅Continuously expanding test coverage

Properly testing across browsers takes a bit more initial effort – but pays back exponentially through happier customers and fewer catastrophic UI bugs down the road.

Have you used Selenium for browser test automation before? Feel free to ask me any setup questions in the comments! Thanks for reading.