Page Object Model Inheritance

Hopefully you already know the importance of using the Page Object Model to keep your code organised. To keep your code maintainable it’s a good practice to have page inherit from a single abstract “BasePage” class. This allows us to have one central place that defines general actions that our pages can perform, and allows our concrete pages to inherit those behaviours, such as:

Finding elements
Clicking elements
Checking whether an element is present
Waiting for an element to become present
Filling in text fields
Selecting items from select lists

But these are all things you can access through the WebDriver API itself right? Yes, but to help write more readable and maintainable code it’s good to limit how much we make direct calls to the WebDriver API. It’s better to have methods that you directly control, that will allow you to make broad changes really easily if they become necessary.

For example, if a new version of Firefox is released that for some reason breaks WebDriver’s ability to know whether a page is ready or not, it’s much easier to fix that in your code by altering your “findElement” method to first wait for that element to be present before trying to use it. This kind of event tends to be few and far between, but it saves a lot of time versus refactoring the hundreds of driver.findElement calls you’ve got littered throughout your code.

	public abstract class BasePage {
	private WebDriver driver;

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

	public WebElement findElement(By by) {
	return driver.findElement(by);
	}

	public void clickElement(By by) {
	findElement(by).click();
	}
	}

view raw

BasePage.java

hosted with ❤ by GitHub

This is our abstract BasePage class, containing a couple of simple methods that allow us to make very quick alterations to every base action that we take in our framework.

When we make a concrete page object, we extend from BasePage:

	public class LoginPage extends BasePage {
	public LoginPage(WebDriver driver) {
	super(driver);
	}

	public void clickLoginButton() {
	clickElement(By.id("loginBtn"));
	}
	}

view raw

LoginPage.java

hosted with ❤ by GitHub

We now have a simple system for sharing a set of common actions between all of our page objects. If we have to change the way we do things down the line, it’s now a one or two line change, rather than hours of work.

When we want to interact with the page, we create an instance of LoginPage and pass in our WebDriver instance:

	public class LoginTest {

	// Simplified JUnit test structure, don't write tests like this!
	@Test
	public void simpleLoginTest() {
	WebDriver driver = new ChromeDriver();

	LoginPage loginPage = new LoginPage(driver);

	loginPage.clickLoginButton();
	}

	}

view raw

LoginTest.java

hosted with ❤ by GitHub

Share this:

Like this:

Leave a Reply Cancel reply