Why Page class structure in Selenium Python? - Purpose & Use Cases

The Big Idea

Discover how organizing your test code by pages can save hours of frustration and bugs!

The Scenario

Imagine testing a website by clicking buttons and filling forms manually every time you want to check if it works.

You write separate code for each page, repeating similar steps everywhere.

The Problem

This manual way is slow and tiring.

Every small change in the website means you must find and fix many places in your code.

It's easy to make mistakes and hard to keep track of what each part does.

The Solution

Using a Page class structure, you create one class for each page of the website.

Each class holds all the buttons, fields, and actions for that page in one place.

This makes your code clean, easy to update, and simple to understand.

Before vs After

✗ Before

driver.find_element(By.ID, 'login').click()
driver.find_element(By.ID, 'username').send_keys('user')
driver.find_element(By.ID, 'password').send_keys('pass')
driver.find_element(By.ID, 'submit').click()

✓ After

class LoginPage:
    def __init__(self, driver):
        self.driver = driver
    def login(self, user, pwd):
        self.driver.find_element(By.ID, 'login').click()
        self.driver.find_element(By.ID, 'username').send_keys(user)
        self.driver.find_element(By.ID, 'password').send_keys(pwd)
        self.driver.find_element(By.ID, 'submit').click()

What It Enables

It enables writing tests that are easy to read, maintain, and reuse across many test cases.

Real Life Example

When a website changes its login button ID, you only update it once inside the LoginPage class instead of searching through all your test scripts.

Key Takeaways

Manual test code is repetitive and hard to maintain.

Page class structure groups page elements and actions logically.

This approach saves time and reduces errors when website changes.

Practice

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

easy

A. To write assertions for test results

B. To store test data for multiple test cases

C. To execute the browser driver directly

D. To group web elements and actions for a single web page

Solution

1. Step 1: Understand the role of page classes

   Page classes organize locators and methods related to one web page, making tests cleaner.

2. Step 2: Identify the correct purpose

   Grouping elements and actions for a page matches the page class concept.

3. Final Answer:

   To group web elements and actions for a single web page -> Option D

4. Quick Check:

   Page class = group elements and actions [OK]

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

Common Mistakes:

• Confusing page class with test data storage
• Thinking page class runs the browser driver
• Mixing page class with assertion logic

2. Which of the following is the correct way to define a locator inside a Selenium page class in Python?

easy

A. submit_button = (By.ID, 'submit')

B. submit_button = 'By.ID, submit'

C. submit_button = By.ID('submit')

D. submit_button = By('ID', 'submit')

Solution

1. Step 1: Recall locator tuple syntax

   Locators use tuples like (By.ID, 'value') to specify how to find elements.

2. Step 2: Check each option

   submit_button = (By.ID, 'submit') correctly uses a tuple with By.ID and string 'submit'. Others have syntax errors or wrong formats.

3. Final Answer:

   submit_button = (By.ID, 'submit') -> Option A

4. Quick Check:

   Locator = (By.METHOD, 'value') tuple [OK]

Hint: Use tuple (By.METHOD, 'value') for locators [OK]

Common Mistakes:

• Using string instead of tuple for locator
• Calling By.ID as a function
• Incorrect tuple structure

3. Given the following page class snippet, what will page.get_title() return if the browser's current page title is "Welcome Page"?

class HomePage:
    def __init__(self, driver):
        self.driver = driver
    def get_title(self):
        return self.driver.title

page = HomePage(driver)

medium

A. An error because get_title is missing

B. "Welcome Page"

C. None

D. "HomePage"

Solution

1. Step 1: Understand get_title method

   The method returns self.driver.title, which is the browser's current page title.

2. Step 2: Check given title

   The browser's title is "Welcome Page", so the method returns this string.

3. Final Answer:

   "Welcome Page" -> Option B

4. Quick Check:

   driver.title returns current page title [OK]

Hint: driver.title gives current page title string [OK]

Common Mistakes:

• Assuming method returns None by default
• Thinking method is missing or undefined
• Confusing class name with page title

4. Identify the error in this page class method and how to fix it:

class LoginPage:
    def __init__(self, driver):
        self.driver = driver
        self.username_input = (By.ID, 'username')
    def enter_username(self, username):
        self.driver.find_element(self.username_input).send_keys(username)

medium

A. Missing return statement in enter_username method

B. send_keys should be called on driver, not element

C. find_element expects two arguments, fix by unpacking locator: *self.username_input

D. Locator should be a string, not a tuple

Solution

1. Step 1: Check find_element usage

   find_element expects two arguments: method and locator string, not a tuple as one argument.

2. Step 2: Fix by unpacking tuple

   Use *self.username_input to unpack tuple into two arguments.

3. Final Answer:

   find_element expects two arguments, fix by unpacking locator: *self.username_input -> Option C

4. Quick Check:

   Use * to unpack locator tuple in find_element [OK]

Hint: Unpack locator tuple with * in find_element [OK]

Common Mistakes:

• Passing locator tuple as single argument
• Calling send_keys on driver instead of element
• Thinking return is required for action methods

5. You want to create a page class for a login page with username and password fields and a login button. Which design best follows the page class structure and good practices?

hard

A. class LoginPage:
def __init__(self, driver):
self.driver = driver
self.username = (By.ID, 'user')
self.password = (By.ID, 'pass')
self.login_btn = (By.ID, 'login')
def enter_username(self, name):
self.driver.find_element(*self.username).send_keys(name)
def enter_password(self, pwd):
self.driver.find_element(*self.password).send_keys(pwd)
def click_login(self):
self.driver.find_element(*self.login_btn).click()

B. class LoginPage:
def __init__(self, driver):
self.driver = driver
def login(self, user, pwd):
self.driver.find_element(By.ID, 'user').send_keys(user)
self.driver.find_element(By.ID, 'pass').send_keys(pwd)
self.driver.find_element(By.ID, 'login').click()

C. class LoginPage:
def __init__(self, driver):
self.driver = driver
self.username = 'user'
self.password = 'pass'
self.login_btn = 'login'
def login(self, user, pwd):
self.driver.find_element(By.ID, self.username).send_keys(user)
self.driver.find_element(By.ID, self.password).send_keys(pwd)
self.driver.find_element(By.ID, self.login_btn).click()

D. class LoginPage:
def __init__(self, driver):
self.driver = driver
def enter_username(self, name):
self.driver.find_element(By.ID, 'user').send_keys(name)
def enter_password(self, pwd):
self.driver.find_element(By.ID, 'pass').send_keys(pwd)
def click_login(self):
self.driver.find_element(By.ID, 'login').click()

Solution

1. Step 1: Check locator storage

   class LoginPage: def __init__(self, driver): self.driver = driver self.username = (By.ID, 'user') self.password = (By.ID, 'pass') self.login_btn = (By.ID, 'login') def enter_username(self, name): self.driver.find_element(*self.username).send_keys(name) def enter_password(self, pwd): self.driver.find_element(*self.password).send_keys(pwd) def click_login(self): self.driver.find_element(*self.login_btn).click() stores locators as tuples in __init__, which is best practice for reuse and clarity.

2. Step 2: Check method structure

   class LoginPage: def __init__(self, driver): self.driver = driver self.username = (By.ID, 'user') self.password = (By.ID, 'pass') self.login_btn = (By.ID, 'login') def enter_username(self, name): self.driver.find_element(*self.username).send_keys(name) def enter_password(self, pwd): self.driver.find_element(*self.password).send_keys(pwd) def click_login(self): self.driver.find_element(*self.login_btn).click() has separate methods for each action, improving readability and maintainability.

3. Step 3: Compare other options

   class LoginPage: def __init__(self, driver): self.driver = driver def login(self, user, pwd): self.driver.find_element(By.ID, 'user').send_keys(user) self.driver.find_element(By.ID, 'pass').send_keys(pwd) self.driver.find_element(By.ID, 'login').click() repeats locators in methods, class LoginPage: def __init__(self, driver): self.driver = driver self.username = 'user' self.password = 'pass' self.login_btn = 'login' def login(self, user, pwd): self.driver.find_element(By.ID, self.username).send_keys(user) self.driver.find_element(By.ID, self.password).send_keys(pwd) self.driver.find_element(By.ID, self.login_btn).click() stores locators as strings only, class LoginPage: def __init__(self, driver): self.driver = driver def enter_username(self, name): self.driver.find_element(By.ID, 'user').send_keys(name) def enter_password(self, pwd): self.driver.find_element(By.ID, 'pass').send_keys(pwd) def click_login(self): self.driver.find_element(By.ID, 'login').click() does not store locators as variables.

4. Final Answer:

   Option A follows page class structure and good practices best -> Option A

5. Quick Check:

   Store locators once, use methods for actions [OK]

Hint: Store locators as tuples, use methods for actions [OK]

Common Mistakes:

• Repeating locators inside methods
• Storing locators as plain strings
• Not separating actions into methods