What common design patterns do you apply in your practice?

In QA practice and test automation, the following design patterns are often used:

• Page Object — for abstraction of elements and actions on web application pages, which simplifies maintenance and reusability of code.

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

• Factory — for creating test data objects or test scenarios with different parameters.

• Builder — for convenient and clear construction of complex test data objects.

• Strategy — for selecting different algorithms or methods of executing tests depending on conditions.

Example of the Page Object pattern in Kotlin:

class LoginPage(private val driver: WebDriver) {
    private val usernameField = driver.findElement(By.id("username"))
    private val passwordField = driver.findElement(By.id("password"))
    private val loginButton = driver.findElement(By.id("login"))

    fun login(username: String, password: String) {
        usernameField.sendKeys(username)
        passwordField.sendKeys(password)
        loginButton.click()
    }
}

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