Can you give examples of design patterns you have used in your projects?

The following design patterns are often used in QA and automation testing:

• Page Object — for abstracting elements and actions on web application pages, which simplifies test maintenance.

• Singleton — for creating a single instance of a driver or configuration manager.

• Factory — for creating test data objects or test environments.

• Builder — for step-by-step creation of complex objects, such as test data with many parameters.

• Observer — for implementing event-driven models, such as tracking changes in the state of the tested application.

Example of the Page Object pattern in Java:

public class LoginPage {
    private WebDriver driver;

    public LoginPage(WebDriver driver) {
        this.driver = driver;
    }

    public void enterUsername(String username) {
        driver.findElement(By.id("username")).sendKeys(username);
    }

    public void enterPassword(String password) {
        driver.findElement(By.id("password")).sendKeys(password);
    }

    public void clickLogin() {
        driver.findElement(By.id("loginButton")).click();
    }
}

Using such patterns increases the readability, maintainability, and scalability of test code.