Automation in Selenium: Page Object Model and Page Factory

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Automation in Selenium: Page Object Model and Page Factory

2023-03-12 07:16| 来源: 网络整理| 查看: 265

Editor’s note: This article was updated on 11/18/2022 by our editorial team. It has been modified to include recent sources and to align with our current editorial standards.

Writing automated tests is more than just a luxury for any agile software development team. It is an essential tool to find bugs quickly during early phases of software development cycles. When there is a new feature that is still in the development phase, developers can run automated tests and see how those changes affect other parts of the system. This article will explain how you can speed up this process with test automation in Selenium, using the Page Object model.

Through test automation, it is possible to reduce the cost of bug fixes and improve the overall software quality assurance (QA) process. With proper tests, developers can find and resolve bugs before they reach QA. Test automation further helps us to automate test cases and features that are constantly regressing. This way, QA engineers have more time to test other parts of the application. Moreover, this helps ensure quality of the product in production releases. As a result, we get products that are effectively more stable, and a QA process that is more efficient.

Selenium simplifies test automation for web applications. Tweet

Although writing automated tests may seem like an easy task for developers and engineers, there is still the possibility of ending up with poorly implemented tests and poor code maintainability. Trying to constantly deliver changes or features in any agile development project can prove to be costly when tests are involved. Changing one element on a webpage that 20 tests rely on will require going through these 20 test routines and updating each one to adapt to this change. This is time consuming and discourages developers from implementing automated tests early on.

But what if we could make the change in one place only and have every relevant test routine use it? We will take a look at automated tests in Selenium, and how we can employ Page Object model best practices to write maintainable and reusable test routines.

Selenium Page Object Model

Page Object model is an object design pattern in Selenium, where webpages are represented as classes, and the various elements on the page are defined as variables on the class. All possible user interactions can then be implemented as methods on the class:

clickLoginButton(); setCredentials(user_name,user_password);

Since well-named methods in classes are easy to read, this works as an elegant way to implement test routines that are both readable and easier to maintain or update in the future. For example:

In order to support Page Object model, we use Page Factory. Page Factory in Selenium is an extension to Page Object and can be used in various ways. In this case we will use Page Factory to initialize web elements that are defined in webpage classes or Page Objects.

Webpage classes or Page Objects containing web elements need to be initialized using Page Factory before the web element variables can be used. This can be done through the use of initElements function on Page Factory:

LoginPage page = new LoginPage(driver); PageFactory.initElements(driver, page);

Or, even simpler:

LoginPage page = PageFactory.intElements(driver,LoginPage.class)

Or, inside the webpage class constructor:

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

Page Factory will initialize every WebElement variable with a reference to a corresponding element on the actual webpage based on configured “locators.” This is done through the use of @FindBy annotations. With this annotation, we can define a strategy for looking up the element, along with the necessary information for identifying it:

@FindBy(how=How.NAME, using="username") private WebElement user_name;

Every time a method is called on this WebElement variable, the driver will first find it on the current page and then simulate the interaction. In case we are working with a simple page, we know that we will find the element on the page every time we look for it, and we also know that we will eventually navigate away from this page without returning. Here, we can cache the looked up field by using another simple annotation:

@FindBy(how=How.NAME, using="username") @CacheLookup private WebElement user_name;

This entire definition of the WebElement variable can be replaced with a much more concise form:

@FindBy(name="username") private WebElement user_name;

The @FindBy annotation supports a handful of other strategies that make things a bit easier, including id, name, className, css, tagName, linkText, partialLinkText, and xpath.

@FindBy(id="username") private WebElement user_name; @FindBy(name="passsword") private WebElement user_password; @FindBy(className="h3") private WebElement label; @FindBy(css=”#content”) private WebElement text;

Once initialized, these WebElement variables can then be used to interact with the corresponding elements on the page. For example, we can send the given sequence of keystrokes to the password field on the page:

user_password.sendKeys(password);

This is equivalent to the following:

driver.findElement(By.name(“user_password”)).sendKeys(password);

Moving on, you will often come across situations where you need to find a list of elements on a page, and that is when @FindBys comes in handy:

@FindBys(@FindBy(css=”div[class=’yt-lockup-tile yt-lockup-video’]”))) private List videoElements;

The above code will find all the div elements having two class names, yt-lockup-tile and yt-lockup-video. We can simplify this even more by replacing it with the following:

@FindBy(how=How.CSS,using="div[class=’yt-lockup-tile yt-lockup-video’]") private List videoElements;

Additionally, you can use @FindAll with multiple @FindBy annotations to look for elements that match any of the given locators:

@FindAll({@FindBy(how=How.ID, using=”username”), @FindBy(className=”username-field”)}) private WebElement user_name;

Now that we can represent webpages as Java classes and use Page Factory to initialize WebElement variables easily, let’s see how to write simple tests using the Page Object pattern and Page Factory in Selenium.

Simple Selenium Test Automation Project in Java

For our Selenium Page Object model tutorial, let’s automate Toptal’s developer sign-up process, which includes the following steps:

Visit www.toptal.com

Click on the Apply As A Developer button

Check if the portal page is opened

Click on the Join Toptal button

Fill out the form

Submit the form by clicking on the Join Toptal button

To execute this automation, we must set up our Java project.

Setting Up a Project

Download and install Java JDK and InteliJ Idea, and then we can proceed:

Create a new Maven project

Link Project SDK to your JDK, e.g.: on Windows C:\Program Files\Java\jdkxxx

Setup groupId (SeleniumTEST) and artifactId (Test)

Add dependencies for Selenium and JUnit Maven in your project POM file; make sure to update selenium.version and junit.version with the latest version numbers for JUnit Maven and Selenium:

junit junit ${junit.version} test org.seleniumhq.selenium selenium-firefox-driver ${selenium.version} org.seleniumhq.selenium selenium-support ${selenium.version} org.seleniumhq.selenium selenium-java ${selenium.version}

At this point, if auto build is enabled, dependencies should start downloading automatically. If not, just activate Plugins > install > install:install under the Maven Projects panel on the right side of your IntelliJ Idea IDE.

selenium testing tutorial IDE screenshot

Once the project has been bootstrapped, we can start creating our test package under src/test/java. Name the package com.toptal, and create two more packages under it: com.toptal.webpages and com.toptal.tests.

selenium testing tutorial screenshot

We will keep our Page Object/Page Factory classes under com.toptal.webpages and the test routines under com.toptal.tests.

We will have three Page Object classes:

Class

Description

HomePage

Represents Toptal's homepage, www.toptal.com

DeveloperPortalPage

Represents Toptal's developer portal page

DeveloperApplyPage

Represents Toptal's developer application form

Now, we are ready to create the Page Object items.

Selenium Page Object Model: HomePage

The very first object we need to implement is for Toptal’s homepage (www.toptal.com). Create a class under com.toptal.webpages and name it HomePage.

package com.toptal.webpages; import org.openqa.selenium.WebDriver; import org.openqa.selenium.WebElement; import org.openqa.selenium.support.FindBy; import org.openqa.selenium.support.How; import org.openqa.selenium.support.PageFactory; public class HomePage { private WebDriver driver; //Page URL private static String PAGE_URL="https://www.toptal.com"; //Locators //Apply as Developer Button @FindBy(how = How.LINK_TEXT, using = "APPLY AS A DEVELOPER") private WebElement developerApplyButton; //Constructor public HomePage(WebDriver driver){ this.driver=driver; driver.get(PAGE_URL); //Initialise Elements PageFactory.initElements(driver, this); } public void clickOnDeveloperApplyButton(){ developerApplyButton.click(); } } Determining Element Locators

On Toptal’s homepage we are interested in one element in particular, and that is the Apply as a Developer button. We can find this element by matching the text, which is what we are doing above. While modeling webpages as Page Object classes, finding and identifying elements can often become a chore. With Firefox Developer Tools or Chrome DevTools, this task can be made easier. By right-clicking on any element on a page, you can activate the Inspect Element option from the context menu to find out detailed information about the element.

By copying the xpath of the element, we can create a WebElement field for it in our Page Object as follows:

@FindBy(xpath = "/html/body/div[1]/div/div/header/div/h1") WebElement heading;

Or, to keep things simple, we can use the tag name “h1” here, as long as it uniquely identifies the element we are interested in:

@FindBy(tagName = "h1") WebElement heading; Selenium Page Object Model: DeveloperPortalPage

Next, we need a Page Object that represents the developer portal page, the one that we can reach by clicking on the Apply As A Developer button.

On this page, we have two elements of interest. To determine if the page has loaded, we want to verify the existence of the heading. And we also want a WebElement field for the Join Toptal button.

package com.toptal.webpages; import org.openqa.selenium.WebDriver; import org.openqa.selenium.WebElement; import org.openqa.selenium.support.FindBy; import org.openqa.selenium.support.PageFactory; public class DeveloperPortalPage { private WebDriver driver; @FindBy(xpath = "/html/body/div[1]/div/div/header/div/h1") private WebElement heading; @FindBy(linkText = "JOIN TOPTAL") private WebElement joinToptalButton; //Constructor public DeveloperPortalPage (WebDriver driver){ this.driver=driver; //Initialise Elements PageFactory.initElements(driver, this); } //We will use this boolean for assertion. To check if page is opened public boolean isPageOpened(){ return heading.getText().toString().contains("Developer portal"); } public void clikOnJoin(){ joinToptalButton.click(); } } Selenium Page Object Model: DeveloperApplyPage

For our third and last page object for this project, we define an object that represents the page containing the developer application form. Since we have to deal with a number of form fields here, we define one WebElement variable for every form field. We find each field by its id, and we define special setter methods for every field that simulate keystrokes for the corresponding fields.

package com.toptal.webpages; import org.openqa.selenium.WebDriver; import org.openqa.selenium.WebElement; import org.openqa.selenium.support.FindBy; import org.openqa.selenium.support.PageFactory; public class DeveloperApplyPage { private WebDriver driver; @FindBy(tagName = "h1") WebElement heading; @FindBy(id="developer_email") WebElement developer_email; @FindBy(id = "developer_password") WebElement developer_password; @FindBy(id = "developer_password_confirmation") WebElement developer_password_confirmation; @FindBy(id = "developer_full_name") WebElement developer_full_name; @FindBy(id = "developer_skype") WebElement developer_skype; @FindBy(id ="save_new_developer") WebElement join_toptal_button; //Constructor public DeveloperApplyPage(WebDriver driver){ this.driver=driver; //Initialise Elements PageFactory.initElements(driver, this); } public void setDeveloper_email(String email){ developer_email.clear(); developer_email.sendKeys(email); } public void setDeveloper_password(String password){ developer_password.clear(); developer_password.sendKeys(password); } public void setDeveloper_password_confirmation(String password_confirmation){ developer_password_confirmation.clear(); developer_password_confirmation.sendKeys(password_confirmation); } public void setDeveloper_full_name (String fullname){ developer_full_name.clear(); developer_full_name.sendKeys(fullname); } public void setDeveloper_skype (String skype){ developer_skype.clear(); developer_skype.sendKeys(skype); } public void clickOnJoin(){ join_toptal_button.click(); } public boolean isPageOpened(){ //Assertion return heading.getText().toString().contains("Apply to join our network as a developer"); } } Writing a Simple Selenium Test

With Page Object classes representing our pages, and user interactions as their methods, we can now write our test routine as a series of simple method calls and assertions.

package com.toptal.tests; import com.toptal.webpages.DeveloperApplyPage; import com.toptal.webpages.DeveloperPortalPage; import com.toptal.webpages.HomePage; import org.junit.After; import org.junit.Assert; import org.junit.Before; import org.junit.Test; import org.openqa.selenium.WebDriver; import org.openqa.selenium.firefox.FirefoxDriver; import java.net.URL; import java.util.concurrent.TimeUnit; public class ApplyAsDeveloperTest { WebDriver driver; @Before public void setup(){ //use FF Driver driver = new FirefoxDriver(); driver.manage().timeouts().implicitlyWait(10, TimeUnit.SECONDS); } @Test public void applyAsDeveloper() { //Create object of HomePage Class HomePage home = new HomePage(driver); home.clickOnDeveloperApplyButton(); //Create object of DeveloperPortalPage DeveloperPortalPage devportal= new DeveloperPortalPage(driver); //Check if page is opened Assert.assertTrue(devportal.isPageOpened()); //Click on Join Toptal devportal.clikOnJoin(); //Create object of DeveloperApplyPage DeveloperApplyPage applyPage =new DeveloperApplyPage(driver); //Check if page is opened Assert.assertTrue(applyPage.isPageOpened()); //Fill up data applyPage.setDeveloper_email("[email protected]"); applyPage.setDeveloper_full_name("Dejan Zivanovic Automated Test"); applyPage.setDeveloper_password("password123"); applyPage.setDeveloper_password_confirmation("password123"); applyPage.setDeveloper_skype("automated_test_skype"); //Click on join //applyPage.clickOnJoin(); } @After public void close(){ driver.close(); } } Running the Test

At this point, your project structure should look like this:

selenium testing example

If you want to run the test, select ApplyAsDeveloperTest from the tree, right-click on it, and select Run ‘ApplyAsDeveloperTest’.

selenium testing example

Once the test has been run, you can see the results in the lower left corner of your IDE:

selenium testing example

Automation in Selenium for Maintainable Test Suites

Page Object and Page Factory in Selenium make it easy to model and automatically test webpages, and make the lives of both developers and QA engineers much simpler. When done right, these Page Object classes can be reused across your entire test suite and make it possible to implement automated Selenium tests for your projects early on, without compromising agile development. By abstracting away user interactions in your page object models and keeping your test routines light and simple, you can adapt your test suite to any requirement changes with little effort.

I hope I have managed to show you how to write nice and clean test code that is easy to maintain. Keep my favorite QA quote in mind: “Think twice, code once!”

Further Reading on the Toptal Engineering Blog: Web Scraping with a Headless Browser: A Puppeteer Tutorial


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