Test class using page objects in Selenium Python - Build an Automation Script

Login functionality test using page objects

Preconditions (2)

Step 1: Open the browser and navigate to 'https://example.com/login'

Step 2: Enter 'testuser' in the username input field

Step 3: Enter 'Test@1234' in the password input field

Step 4: Click the login button

Step 5: Wait for the dashboard page to load

✅ Expected Result: User is successfully logged in and the dashboard page URL contains '/dashboard'

Automation Requirements - Selenium with Python unittest

Assertions Needed:

Verify the current URL contains '/dashboard' after login

Verify the login button is clickable before clicking

Verify username and password fields are present before input

Best Practices:

Use Page Object Model to separate page elements and actions

Use explicit waits to wait for elements to be interactable

Use unittest framework for test structure and assertions

Keep locators in the page object class using By selectors

Automated Solution

Selenium Python

import unittest
from selenium import webdriver
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC

class LoginPage:
    URL = "https://example.com/login"
    USERNAME_INPUT = (By.ID, "username")
    PASSWORD_INPUT = (By.ID, "password")
    LOGIN_BUTTON = (By.ID, "loginBtn")

    def __init__(self, driver):
        self.driver = driver

    def load(self):
        self.driver.get(self.URL)

    def enter_username(self, username):
        WebDriverWait(self.driver, 10).until(
            EC.visibility_of_element_located(self.USERNAME_INPUT)
        ).send_keys(username)

    def enter_password(self, password):
        WebDriverWait(self.driver, 10).until(
            EC.visibility_of_element_located(self.PASSWORD_INPUT)
        ).send_keys(password)

    def click_login(self):
        login_button = WebDriverWait(self.driver, 10).until(
            EC.element_to_be_clickable(self.LOGIN_BUTTON)
        )
        login_button.click()

class TestLogin(unittest.TestCase):
    def setUp(self):
        self.driver = webdriver.Chrome()
        self.driver.maximize_window()
        self.login_page = LoginPage(self.driver)

    def test_valid_login(self):
        self.login_page.load()
        self.login_page.enter_username("testuser")
        self.login_page.enter_password("Test@1234")
        self.login_page.click_login()

        WebDriverWait(self.driver, 10).until(
            EC.url_contains("/dashboard")
        )
        current_url = self.driver.current_url
        self.assertIn("/dashboard", current_url, "Dashboard URL not found after login")

    def tearDown(self):
        self.driver.quit()

if __name__ == "__main__":
    unittest.main()

This test uses the Page Object Model to keep the login page elements and actions in the LoginPage class. This makes the test code cleaner and easier to maintain.

The LoginPage class defines locators as tuples using By.ID for better readability and maintainability.

Explicit waits (WebDriverWait) ensure the test waits for elements to be visible or clickable before interacting, avoiding flaky tests.

The test class TestLogin uses Python's unittest framework for structure and assertions.

Setup and teardown methods open and close the browser for each test, ensuring a clean state.

The test verifies the URL contains '/dashboard' after login to confirm success.

Common Mistakes - 3 Pitfalls

Using hardcoded sleep instead of explicit waits

Locating elements directly in the test instead of using page objects

Not verifying elements are present before interacting

Bonus Challenge

Now add data-driven testing with 3 different sets of username and password inputs to test multiple login scenarios.

Show Hint

Practice

1. What is the main purpose of using a page object in Selenium test classes?

easy

A. To separate page details from test logic for easier maintenance

B. To write all test steps inside the test class directly

C. To avoid using locators in tests

D. To run tests faster by skipping page loading

Solution

1. Step 1: Understand page object role

   Page objects hold locators and page actions, separating them from test logic.

2. Step 2: Recognize test class role

   Test classes use page objects to perform actions and assertions, improving readability and maintenance.

3. Final Answer:

   To separate page details from test logic for easier maintenance -> Option A

4. Quick Check:

   Page objects separate page details = C [OK]

Hint: Page objects keep page info separate from tests [OK]

Common Mistakes:

• Thinking tests should contain locators directly
• Believing page objects speed up test execution
• Confusing page objects with test runners

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

easy

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

B. def LoginPage(driver):
username_input = driver.find_element(By.ID, 'username')

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

D. class LoginPage:
def __init__(self, driver):
self.username_input = driver.find_element('username')

Solution

1. Step 1: Check class and constructor syntax

   class LoginPage: def __init__(self, driver): self.driver = driver self.username_input = driver.find_element(By.ID, 'username') correctly defines a class with __init__ accepting driver and assigns driver to self.driver.

2. Step 2: Verify locator usage

   class LoginPage: def __init__(self, driver): self.driver = driver self.username_input = driver.find_element(By.ID, 'username') uses driver.find_element with By.ID and locator string, which is correct Selenium syntax.

3. Final Answer:

   Correct page object class with driver parameter and locator using By.ID -> Option C

4. Quick Check:

   Class with __init__(driver) and By.ID locator = A [OK]

Hint: Page object classes need __init__(self, driver) and proper locators [OK]

Common Mistakes:

• Missing driver parameter in __init__
• Using driver.find_element without By selector
• Defining page object as a function instead of class

3. Given the following test class using a page object, what will be printed if the username input is found and the page title is 'Login Page'?

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

class TestLogin:
    def test_title(self, driver):
        page = LoginPage(driver)
        print(page.get_title())

# Assume driver.title = 'Login Page'

medium

A. None

B. Login Page

C. driver.title

D. Error: driver not defined

Solution

1. Step 1: Understand get_title method

   get_title returns driver.title, which is 'Login Page' as given.

2. Step 2: Check test_title method output

   test_title creates LoginPage instance and prints get_title result, so it prints 'Login Page'.

3. Final Answer:

   Login Page -> Option B

4. Quick Check:

   page.get_title() returns 'Login Page' [OK]

Hint: get_title returns driver.title, prints page title string [OK]

Common Mistakes:

• Confusing method return with attribute name
• Assuming print outputs None
• Thinking driver is undefined inside test method

4. Identify the error in this test class using a page object:

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

class TestLogin:
    def test_enter_username(self, driver):
        page = LoginPage()
        page.enter_username('user1')

medium

A. LoginPage is instantiated without driver argument

B. send_keys method is called incorrectly

C. By.ID locator is invalid

D. test_enter_username method missing self parameter

Solution

1. Step 1: Check LoginPage instantiation

   LoginPage requires driver argument in __init__, but called without arguments in test_enter_username.

2. Step 2: Verify other code parts

   send_keys usage and By.ID locator are correct; test_enter_username has self parameter as method of class.

3. Final Answer:

   LoginPage is instantiated without driver argument -> Option A

4. Quick Check:

   Missing driver argument in LoginPage() call = B [OK]

Hint: Check constructor arguments when creating page object instances [OK]

Common Mistakes:

• Forgetting to pass driver to page object constructor
• Assuming send_keys needs different syntax
• Confusing locator syntax errors

5. You want to write a test class that uses a page object to check if a login button is visible and clickable. Which approach correctly combines page object and test class methods?

hard

A. Test class calls page object method that returns the button WebElement but does not check visibility

B. Test class directly uses driver.find_element to check button visibility, ignoring page object

C. Page object only stores locators; test class performs all actions and assertions

D. Page object has method is_login_button_clickable() returning True/False; test class asserts this method's result

Solution

1. Step 1: Understand page object responsibility

   Page objects should provide methods that check element states like visibility and clickability.

2. Step 2: Understand test class responsibility

   Test class uses page object methods to assert expected conditions, keeping test logic separate from page details.

3. Final Answer:

   Page object has method is_login_button_clickable() returning True/False; test class asserts this method's result -> Option D

4. Quick Check:

   Page object checks state, test asserts result = D [OK]

Hint: Page object checks element state; test asserts result [OK]

Common Mistakes:

• Mixing locator logic inside test class
• Not returning boolean from page object methods
• Ignoring visibility checks in tests