Why POM creates maintainable test code in Selenium Java - Test Execution Impact

Test Overview

This test verifies that the Page Object Model (POM) helps keep test code maintainable by separating page structure from test logic. It checks that changes in the page only require updates in one place, making tests easier to maintain.

Test Code - JUnit with Selenium WebDriver

Selenium Java

import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.chrome.ChromeDriver;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import static org.junit.jupiter.api.Assertions.assertEquals;

// Page Object for Login Page
class LoginPage {
    private WebDriver driver;
    private By usernameField = By.id("username");
    private By passwordField = By.id("password");
    private By loginButton = By.id("loginBtn");

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

    public void enterUsername(String username) {
        driver.findElement(usernameField).sendKeys(username);
    }

    public void enterPassword(String password) {
        driver.findElement(passwordField).sendKeys(password);
    }

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

// Test class
public class LoginTest {
    private WebDriver driver;
    private LoginPage loginPage;

    @BeforeEach
    public void setUp() {
        driver = new ChromeDriver();
        driver.get("https://example.com/login");
        loginPage = new LoginPage(driver);
    }

    @Test
    public void testValidLogin() {
        loginPage.enterUsername("user1");
        loginPage.enterPassword("pass123");
        loginPage.clickLogin();

        String expectedUrl = "https://example.com/dashboard";
        String actualUrl = driver.getCurrentUrl();
        assertEquals(expectedUrl, actualUrl, "User should be redirected to dashboard after login");
    }

    @AfterEach
    public void tearDown() {
        driver.quit();
    }
}

Execution Trace - 7 Steps

Step	Action	System State	Assertion	Result
1	Test starts and Chrome browser opens	Browser is open at https://example.com/login page	—	PASS
2	LoginPage object is created with driver	Page Object ready to interact with login page elements	—	PASS
3	Enter username 'user1' in username field using LoginPage method	Username field filled with 'user1'	—	PASS
4	Enter password 'pass123' in password field using LoginPage method	Password field filled with 'pass123'	—	PASS
5	Click login button using LoginPage method	Login button clicked, browser navigates to dashboard	—	PASS
6	Verify current URL is https://example.com/dashboard	Browser URL is https://example.com/dashboard	Assert current URL equals expected dashboard URL	PASS
7	Test ends and browser closes	Browser closed	—	PASS

Failure Scenario

Failing Condition: If the locator in LoginPage is incorrect or page structure changes without updating LoginPage

Execution Trace Quiz - 3 Questions

Why does using the LoginPage class help maintain test code?

A Because all locators and actions are in one place, so changes affect only this class

B Because it runs tests faster

C Because it removes the need for assertions

D Because it automatically fixes broken locators

Key Result

Using Page Object Model keeps locators and page actions in one place, so when the web page changes, only the page object needs updating, making tests easier to maintain and less error-prone.

Practice

1. What is the main reason the Page Object Model (POM) helps create maintainable test code?

easy

A. It runs tests faster by using parallel execution.

B. It separates page structure from test logic, making updates easier.

C. It requires less code to write tests.

D. It automatically fixes broken tests.

Solution

1. Step 1: Understand POM structure

   POM organizes code by separating page details (locators, actions) from test steps.

2. Step 2: Identify maintenance benefit

   This separation means if the page changes, only the page object needs updating, not all tests.

3. Final Answer:

   It separates page structure from test logic, making updates easier. -> Option B

4. Quick Check:

   Separation of concerns = easier maintenance [OK]

Hint: Remember: POM separates page and test code for easy updates [OK]

Common Mistakes:

• Thinking POM speeds up test execution
• Believing POM reduces code amount drastically
• Assuming POM auto-fixes test failures

2. Which of the following is the correct way to define a WebElement in a Page Object class using Selenium Java?

easy

A. WebElement button = driver.findElement(By.name);

B. WebElement button = driver.findElement("submit");

C. WebElement button = driver.findElement(By.id("submit"));

D. WebElement button = driver.findElement(By.id);

Solution

1. Step 1: Recall correct syntax for locating elements

   In Selenium Java, findElement requires a By locator like By.id("value").

2. Step 2: Check each option

   WebElement button = driver.findElement(By.id("submit")); uses By.id with a string, which is correct. Others miss the locator type or string.

3. Final Answer:

   WebElement button = driver.findElement(By.id("submit")); -> Option C

4. Quick Check:

   Use By.id("value") for locating elements [OK]

Hint: Use By.id("value") or By.name("value") with findElement [OK]

Common Mistakes:

• Omitting the locator type (By.id, By.name)
• Passing locator type without string
• Using findElement with just a string

3. Given the following Page Object method, what will be the output when calling loginPage.getTitle() if the page title is "Welcome Page"?

public class LoginPage {
  WebDriver driver;
  public LoginPage(WebDriver driver) {
    this.driver = driver;
  }
  public String getTitle() {
    return driver.getTitle();
  }
}

medium

A. "Welcome Page"

B. "Login Page"

C. null

D. Throws NullPointerException

Solution

1. Step 1: Understand getTitle() method

   The method returns the title of the current page from the WebDriver.

2. Step 2: Given page title is "Welcome Page"

   Calling getTitle() returns the actual page title string, which is "Welcome Page".

3. Final Answer:

   "Welcome Page" -> Option A

4. Quick Check:

   driver.getTitle() returns current page title [OK]

Hint: driver.getTitle() returns the current page title string [OK]

Common Mistakes:

• Confusing method return with page object name
• Assuming method returns null or exception without driver
• Thinking getTitle() returns page URL

4. Identify the error in this Page Object method and how to fix it:

public void clickLogin() {
  WebElement loginBtn = driver.findElement(By.id);
  loginBtn.click();
}

medium

A. loginBtn should be declared as WebElement[] instead of WebElement.

B. click() method cannot be called on WebElement.

C. driver.findElement should be replaced with driver.findElements.

D. By.id is missing the locator string; fix by adding the id value.

Solution

1. Step 1: Check findElement syntax

   By.id requires a string argument like By.id("loginBtn"), but here it is missing.

2. Step 2: Fix the locator

   Add the id string inside By.id, e.g., By.id("loginBtn") to correctly locate the element.

3. Final Answer:

   By.id is missing the locator string; fix by adding the id value. -> Option D

4. Quick Check:

   By.id("value") needs a string argument [OK]

Hint: Always provide locator string inside By.id("value") [OK]

Common Mistakes:

• Omitting the locator string in By.id
• Using findElements when only one element needed
• Thinking click() is invalid on WebElement

5. How does using the Page Object Model (POM) save time when the website under test changes its layout or element locators?

hard

A. Only the Page Object classes need updates, not all test scripts.

B. Tests automatically adapt without any code changes.

C. POM uses AI to detect and fix locator changes.

D. Test scripts are deleted and rewritten faster.

Solution

1. Step 1: Understand POM's separation of concerns

   POM keeps locators and page actions inside Page Object classes, separate from test logic.

2. Step 2: Effect of website changes

   If locators or layout change, only the Page Object classes need updating, so tests remain unchanged.

3. Final Answer:

   Only the Page Object classes need updates, not all test scripts. -> Option A

4. Quick Check:

   Update page objects, keep tests stable [OK]

Hint: Update page objects only when UI changes, not all tests [OK]

Common Mistakes:

• Believing tests auto-update without code changes
• Thinking POM uses AI or automation to fix locators
• Assuming tests must be rewritten after UI changes