What design patterns are used for organizing the storage of locators in automation UI?

In UI automation for organizing locator storage, the following design patterns are often used:

• Page Object — each screen or page of the application is represented by a separate class, where locators and interaction methods with elements are encapsulated. This improves readability and test maintenance.

• Singleton — a singleton can be used to store and access locators or configurations to ensure a single source of data.

• Factory — sometimes used to dynamically create page or element objects, especially if there are different page variants.

Example of a simple Page Object in Python with Selenium:

class LoginPage:
    def __init__(self, driver):
        self.driver = driver
        self.username_locator = "#username"
        self.password_locator = "#password"
        self.login_button_locator = "#login"

    def enter_username(self, username):
        self.driver.find_element_by_css_selector(self.username_locator).send_keys(username)

    def enter_password(self, password):
        self.driver.find_element_by_css_selector(self.password_locator).send_keys(password)

    def click_login(self):
        self.driver.find_element_by_css_selector(self.login_button_locator).click()

This approach separates test logic from locator details and simplifies maintenance.