Introduction to Selenium

Selenium is an open-source automation testing tool used for automating web applications. It supports multiple programming languages such as Java, Python, C#, JavaScript, and runs on various browsers like Chrome, Firefox, Edge, and Safari.

🚀 Why Selenium?
✔ Free & Open Source
✔ Supports Multiple Browsers
✔ Cross-Platform Support (Windows, macOS, Linux)
✔ Multiple Language Support (Java, Python, C#, JavaScript, etc.)
✔ Integration with Testing Frameworks (TestNG, JUnit, PyTest, etc.)
✔ Parallel Test Execution (Selenium Grid)

1. Selenium Components

Selenium is not a single tool but a suite of tools:

1️⃣ Selenium WebDriver

  • Used to automate web applications by simulating user interactions.
  • Supports multiple browsers (Chrome, Firefox, Edge, etc.).
  • Provides powerful methods to handle web elements.

2️⃣ Selenium IDE (Integrated Development Environment)

  • A browser extension for Chrome & Firefox.
  • Allows recording and playback of test scripts without coding.
  • Best for beginners but not suitable for advanced automation.

3️⃣ Selenium Grid

  • Allows parallel test execution on multiple browsers and machines.
  • Used for distributed testing.
  • Reduces test execution time.

2. Setting Up Selenium WebDriver

To automate browsers, you need to set up Selenium WebDriver in your system.

Step 1: Install Java & IDE

  • Download and install Java JDK (if not installed).
  • Install an IDE like Eclipse or IntelliJ IDEA.

Step 2: Download Selenium WebDriver

Step 3: Install Browser Drivers

Step 4: Add WebDriver in Java Project

  • Create a Java Project in Eclipse/IntelliJ.
  • Add Selenium JAR files in the project’s build path.

3. Writing Your First Selenium Script

Let’s write a basic Selenium script to open a website and fetch its title.

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.chrome.ChromeDriver;

public class FirstSeleniumTest {
    public static void main(String[] args) {
        // Set ChromeDriver path
        System.setProperty("webdriver.chrome.driver", "path/to/chromedriver.exe");
        
        // Launch browser
        WebDriver driver = new ChromeDriver();
        
        // Open Google
        driver.get("https://www.google.com");
        
        // Print title of the page
        System.out.println("Page Title: " + driver.getTitle());
        
        // Close the browser
        driver.quit();
    }
}

📌 Explanation:
✔ Launches Chrome browser
✔ Opens Google.com
✔ Prints the page title
✔ Closes the browser

4. Locators in Selenium WebDriver

To interact with web elements like buttons, text fields, checkboxes, Selenium uses locators.

Locator Syntax Example
ID By.id("username") driver.findElement(By.id("username"));
Name By.name("password") driver.findElement(By.name("password"));
Class Name By.className("login-button") driver.findElement(By.className("btn-primary"));
Tag Name By.tagName("input") driver.findElement(By.tagName("input"));
Link Text By.linkText("Click Here") driver.findElement(By.linkText("Click Here"));
Partial Link Text By.partialLinkText("Click") driver.findElement(By.partialLinkText("Click"));
CSS Selector By.cssSelector("#login") driver.findElement(By.cssSelector("#login"));
XPath By.xpath("//input[@name='username']") driver.findElement(By.xpath("//input[@name='username']"));

5. Interacting with Web Elements

Selenium allows user interaction with elements using different methods.

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.chrome.ChromeDriver;

public class WebElementActions {
    public static void main(String[] args) {
        WebDriver driver = new ChromeDriver();
        driver.get("https://example.com");

        // Locate elements
        WebElement username = driver.findElement(By.id("username"));
        WebElement loginButton = driver.findElement(By.id("login"));

        // Enter text
        username.sendKeys("testuser");

        // Click button
        loginButton.click();

        // Retrieve text
        String message = driver.findElement(By.id("welcomeMessage")).getText();
        System.out.println("Welcome Message: " + message);

        // Close browser
        driver.quit();
    }
}

✔ sendKeys("text") – Enters text in input fields
✔ click() – Clicks buttons, checkboxes, radio buttons
✔ getText() – Retrieves text from elements

6. Handling Pop-ups, Alerts & Frames

Handling Alerts

driver.switchTo().alert().accept(); // Click OK
driver.switchTo().alert().dismiss(); // Click Cancel
driver.switchTo().alert().sendKeys("Text"); // Enter text

Handling Frames

driver.switchTo().frame("frameName");
driver.switchTo().defaultContent(); // Exit frame

Handling Windows

String mainWindow = driver.getWindowHandle();
for (String window : driver.getWindowHandles()) {
    driver.switchTo().window(window);
}
driver.switchTo().window(mainWindow); // Switch back to main window

7. Selenium Waits

Selenium provides Implicit and Explicit Waits to handle dynamic elements.

Implicit Wait

driver.manage().timeouts().implicitlyWait(Duration.ofSeconds(10));

Explicit Wait

WebDriverWait wait = new WebDriverWait(driver, Duration.ofSeconds(10));
wait.until(ExpectedConditions.visibilityOfElementLocated(By.id("login")));

8. Running Selenium in Headless Mode

Headless mode allows Selenium to run tests without opening a browser window.

ChromeOptions options = new ChromeOptions();
options.addArguments("--headless");
WebDriver driver = new ChromeDriver(options);

9. Best Practices in Selenium

✅ Use Explicit Waits instead of Thread.sleep()
✅ Use Page Object Model (POM) for better maintainability
✅ Use CSS Selector/XPath efficiently for stable locators
✅ Run tests in headless mode for fast execution
✅ Use parallel execution for large test suites

10. Conclusion

Selenium is a powerful tool for automating web applications. With features like cross-browser support, multiple language integration, and headless execution, it is widely used in the software testing industry.