Why Page class design in Selenium Java? - Purpose & Use Cases

The Big Idea

What if you could fix all your broken tests by changing just one file?

The Scenario

Imagine testing a website by writing code that directly finds and clicks buttons everywhere in your test scripts.

Every time the page changes, you must update many places in your code.

The Problem

This manual way is slow and confusing.

When locators change, you waste hours fixing many test scripts.

It's easy to make mistakes and hard to keep tests working.

The Solution

Page class design groups all page details in one place.

Tests call simple methods like loginPage.clickLogin() instead of repeating locator code.

This makes tests cleaner and easier to fix.

Before vs After

✗ Before

driver.findElement(By.id("loginBtn")).click();
driver.findElement(By.id("username")).sendKeys("user");

✓ After

loginPage.enterUsername("user");
loginPage.clickLogin();

What It Enables

It enables fast, clear, and maintainable tests that adapt easily to page changes.

Real Life Example

When a website changes button IDs, you update only the page class, not every test script.

Key Takeaways

Manual locator use spreads repeated code and errors.

Page class design centralizes page details for easy updates.

Tests become simpler, faster to write, and easier to maintain.

Practice

1. What is the main purpose of a page class in Selenium Java?

easy

A. To handle API requests

B. To write test assertions directly

C. To group web page elements and actions in one place

D. To manage database connections

Solution

1. Step 1: Understand the role of page classes

   Page classes organize locators and actions related to a specific web page.

2. Step 2: Identify the main purpose

   This organization improves code readability and reuse by keeping page details in one place.

3. Final Answer:

   To group web page elements and actions in one place -> Option C

4. Quick Check:

   Page class purpose = Group elements and actions [OK]

Hint: Page classes group elements and actions per page [OK]

Common Mistakes:

• Confusing page classes with test classes
• Using page classes for database or API logic
• Writing assertions inside page classes

2. Which of the following is the correct way to declare a locator in a Selenium page class using Java?

easy

A. public void submitButton = driver.findElement(By.id("submit"));

B. public String submitButton = "submit";

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

D. private By submitButton = By.id("submit");

Solution

1. Step 1: Recall best practice for locators

   Locators should be stored as By objects, not WebElement, to delay element lookup.

2. Step 2: Check each option

   private By submitButton = By.id("submit"); correctly declares a private By locator with By.id("submit").

3. Final Answer:

   private By submitButton = By.id("submit"); -> Option D

4. Quick Check:

   Locators = By objects [OK]

Hint: Use By for locators, not WebElement directly [OK]

Common Mistakes:

• Declaring locators as WebElement fields
• Using public visibility for locators
• Assigning void type to variables

3. Given the following page class snippet, what will loginPage.getTitle() return if the page title is "Welcome Page"?

public class LoginPage {
  private 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 calls driver.getTitle(), which returns the current page title.

2. Step 2: Match with given page title

   The page title is "Welcome Page", so getTitle() returns this string.

3. Final Answer:

   "Welcome Page" -> Option A

4. Quick Check:

   driver.getTitle() = "Welcome Page" [OK]

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

Common Mistakes:

• Assuming getTitle() returns page class name
• Expecting null if not set explicitly
• Confusing with element text retrieval

4. Identify the error in this page class method:

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

medium

A. No error, method is correct

B. Should store locator as a By field, not find element inside method

C. Missing exception handling for element not found

D. Method should return WebElement instead of void

Solution

1. Step 1: Review locator usage best practice

   Locators should be stored as By fields in the page class, not found inside methods.

2. Step 2: Identify the problem

   Finding element inside method reduces reuse and violates page class design principles.

3. Final Answer:

   Should store locator as a By field, not find element inside method -> Option B

4. Quick Check:

   Locators as By fields = best practice [OK]

Hint: Keep locators as fields, find elements in methods [OK]

Common Mistakes:

• Finding elements repeatedly inside methods
• Ignoring locator reuse
• Assuming exception handling is mandatory here

5. You want to design a page class for a login page with username, password fields, and a login button. Which design approach is best to follow?

hard

A. Store locators as private By fields; create public methods to enter username, enter password, and click login

B. Store WebElement fields publicly and access them directly in tests

C. Write all test steps inside the page class constructor

D. Use static methods only without storing any locators

Solution

1. Step 1: Recall page class design principles

   Locators should be private By fields; actions should be public methods for reuse and encapsulation.

2. Step 2: Evaluate options

   Store locators as private By fields; create public methods to enter username, enter password, and click login follows best practice by separating locators and actions clearly.

3. Final Answer:

   Store locators as private By fields; create public methods to enter username, enter password, and click login -> Option A

4. Quick Check:

   Private locators + public methods = best design [OK]

Hint: Private locators + public action methods = good page class [OK]

Common Mistakes:

• Making locators public and exposing WebElements
• Putting test logic in constructors
• Using static methods without instance context