Selenium Cross Browser Testing

Visitors reach a website through Chrome, Firefox, Safari, and Edge, each rendering CSS and JavaScript slightly differently. A button that looks perfect in Chrome might overlap text in Safari. Cross browser testing runs the same test script across multiple browsers to catch these differences early.

Diagram: Same Test, Different Browsers

        [Test Script: verifyCheckoutButton]
         /            |             \
        v              v              v
     Chrome         Firefox           Edge
   (pass)          (pass)           (fail - button hidden)

Writing Browser-Agnostic Code

A driver factory method returns the correct WebDriver based on a parameter, keeping test logic separate from browser choice.

public WebDriver getDriver(String browserName) {
    if (browserName.equalsIgnoreCase("chrome")) {
        return new ChromeDriver();
    } else if (browserName.equalsIgnoreCase("firefox")) {
        return new FirefoxDriver();
    } else if (browserName.equalsIgnoreCase("edge")) {
        return new EdgeDriver();
    }
    throw new IllegalArgumentException("Browser not supported: " + browserName);
}

This method builds the correct driver object based on a text value, letting the same test run on any listed browser.

Parameterizing Browser Choice With TestNG

<suite name="CrossBrowserSuite">
  <test name="ChromeTest">
    <parameter name="browser" value="chrome"/>
    <classes>
      <class name="tests.CheckoutTest"/>
    </classes>
  </test>
  <test name="FirefoxTest">
    <parameter name="browser" value="firefox"/>
    <classes>
      <class name="tests.CheckoutTest"/>
    </classes>
  </test>
</suite>

This XML file runs the exact same CheckoutTest class twice, once against Chrome and once against Firefox.

Reading The Browser Parameter In Code

@Parameters("browser")
@BeforeMethod
public void setUp(String browser) {
    driver = getDriver(browser);
}

TestNG passes the browser value from the XML file directly into this setup method before each test runs.

Cross Browser Testing With Selenium Grid

Selenium Grid distributes tests across multiple machines and browser versions at once, running them in parallel instead of one after another. A team can trigger tests on Chrome, Firefox, and Edge simultaneously, cutting total run time to match the slowest single browser instead of the sum of all three.

Diagram: Selenium Grid Distribution

       [Hub - receives test requests]
        /          |            \
       v            v             v
   [Node: Chrome] [Node: Firefox] [Node: Edge]

Cloud-Based Cross Browser Platforms

Services like BrowserStack and Sauce Labs host real browsers and real devices in the cloud, removing the need to install every browser version locally. Teams connect their existing Selenium scripts to these platforms through a modified driver URL, gaining access to hundreds of browser and OS combinations.

Practical Example

A course pricing page test checks that the Buy Now button remains visible without horizontal scrolling. Running this single test across Chrome, Firefox, and Safari through Selenium Grid reveals that Safari renders the button slightly off-screen, a bug the team would have missed testing on Chrome alone.