Page factory pattern in Selenium Python - Test Execution Trace

Test Overview

This test uses the Page Factory pattern to locate and interact with a login page's username, password fields, and login button. It verifies that after login, the page shows a welcome message.

Test Code - Selenium

Selenium Python

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
from selenium.webdriver.support.page_factory import PageFactory
import unittest

class LoginPage:
    username = (By.ID, "username")
    password = (By.ID, "password")
    login_button = (By.ID, "loginBtn")

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

    def login(self, user, pwd):
        self.username.clear()
        self.username.send_keys(user)
        self.password.clear()
        self.password.send_keys(pwd)
        self.login_button.click()

class TestLogin(unittest.TestCase):
    def setUp(self):
        self.driver = webdriver.Chrome()
        self.driver.get("https://example.com/login")
        self.login_page = LoginPage(self.driver)

    def test_valid_login(self):
        self.login_page.login("testuser", "testpass")
        # Wait for welcome message
        welcome = WebDriverWait(self.driver, 10).until(
            EC.presence_of_element_located((By.ID, "welcomeMsg"))
        )
        self.assertEqual(welcome.text, "Welcome, testuser!")

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

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

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Test starts and Chrome browser opens	Browser window is open at https://example.com/login	—	PASS
2	LoginPage object initializes and locates username, password, and login button elements using PageFactory	Username, password fields and login button are found on the page	—	PASS
3	Test inputs 'testuser' in username field and 'testpass' in password field, then clicks login button	Login form is submitted	—	PASS
4	Waits up to 10 seconds for welcome message element with ID 'welcomeMsg' to appear	Welcome message element appears with text 'Welcome, testuser!'	Check that welcome message text equals 'Welcome, testuser!'	PASS
5	Test ends and browser closes	Browser window is closed	—	PASS

Failure Scenario

Failing Condition: Welcome message element with ID 'welcomeMsg' does not appear after login

Execution Trace Quiz - 3 Questions

What does the Page Factory pattern help with in this test?

A Locating and initializing web elements once for reuse

B Automatically generating test data

C Running tests in parallel

D Capturing screenshots on failure

Key Result

Using the Page Factory pattern helps keep element locators organized and reusable, making tests easier to maintain and read.

Practice

1. What is the main purpose of using the Page Factory pattern in Selenium with Python?

easy

A. To generate test reports automatically

B. To execute tests faster by parallel processing

C. To group web elements in a class for easier access and maintenance

D. To handle browser pop-ups and alerts

Solution

1. Step 1: Understand the role of Page Factory

   Page Factory helps organize web elements by grouping them in a class, making tests easier to read and maintain.

2. Step 2: Compare with other options

   Options B, C, and D describe different Selenium features unrelated to Page Factory's main purpose.

3. Final Answer:

   To group web elements in a class for easier access and maintenance -> Option C

4. Quick Check:

   Page Factory = Group elements for easy access [OK]

Hint: Page Factory groups elements in classes for neat tests [OK]

Common Mistakes:

• Confusing Page Factory with test execution speed
• Thinking it generates reports
• Assuming it handles browser alerts

2. Which of the following is the correct way to declare a web element using Page Factory in Selenium Python?

easy

A. element = driver.find_element(By.ID, 'username')

B. username = (By.ID, 'username')

C. username = self.driver.find_element_by_id('username')

D. username = self.driver.find_element(By.ID, 'username')

Solution

1. Step 1: Identify Page Factory syntax in Python

   Page Factory uses class attributes with locator tuples like (By.ID, 'username') to declare elements before initializing them.

2. Step 2: Check each option

   username = (By.ID, 'username') shows the correct locator tuple usage, which is standard in Page Factory.

3. Final Answer:

   username = (By.ID, 'username') -> Option B

4. Quick Check:

   Page Factory uses locator tuples (By.xx, 'value') [OK]

Hint: Declare Page Factory elements as (By.xx, 'value') tuples [OK]

Common Mistakes:

• Using direct driver.find_element calls instead of Page Factory declarations
• Missing the locator tuple syntax
• Assigning elements directly without initialization

3. Given the following code snippet using Page Factory in Selenium Python, what will be the output of print(page.login_button.is_displayed()) if the button is visible on the page?

from selenium.webdriver.common.by import By
from selenium.webdriver.support.page_factory import PageFactory

class LoginPage:
    def __init__(self, driver):
        self.driver = driver
        PageFactory.init_elements(driver, self)

    login_button = (By.ID, 'loginBtn')

page = LoginPage(driver)
print(page.login_button.is_displayed())

medium

A. True

B. False

C. AttributeError

D. None

Solution

1. Step 1: Understand Page Factory element initialization

   PageFactory.init_elements initializes elements so login_button refers to the actual web element.

2. Step 2: Check the method call

   If the button is visible, is_displayed() returns True, so printing it outputs True.

3. Final Answer:

   True -> Option A

4. Quick Check:

   Visible element's is_displayed() = True [OK]

Hint: is_displayed() returns True if element is visible [OK]

Common Mistakes:

• Expecting None because locator needs initialization
• Confusing AttributeError due to wrong initialization
• Assuming is_displayed() returns string

4. Identify the error in the following Page Factory code snippet and choose the correct fix:

from selenium.webdriver.common.by import By
from selenium.webdriver.support.page_factory import PageFactory

class HomePage:
    def __init__(self, driver):
        self.driver = driver
        PageFactory.init_elements(self, self.driver)

    submit_button = (By.XPATH, "//button[@id='submit']")

page = HomePage(driver)
page.submit_button.click()

medium

A. Initialize elements with PageFactory.init_elements(driver, self)

B. Replace @FindBy with @find_by (lowercase)

C. Import FindBy from correct module and use it as decorator

D. Import and use find_element instead of PageFactory

Solution

1. Step 1: Check PageFactory.init_elements arguments

   The code uses PageFactory.init_elements(self, self.driver) but arguments must be driver first, then self.

2. Step 2: Confirm correct usage

   Using PageFactory.init_elements(driver, self) fixes the error and allows proper element initialization.

3. Final Answer:

   Initialize elements with PageFactory.init_elements(driver, self) -> Option A

4. Quick Check:

   init_elements(driver, self) order [OK]

Hint: PageFactory.init_elements(driver, self) - driver first [OK]

Common Mistakes:

• Wrong argument order for PageFactory.init_elements
• Using wrong decorator name case
• Incorrect PageFactory.init_elements parameters

5. You want to create a Page Factory class for a login page with username, password fields, and a login button. Which approach correctly applies the Page Factory pattern to initialize and use these elements in Selenium Python?

hard

A. Write all element locators inside test functions without any class or decorator

B. Use driver.find_element calls inside each test method without class grouping

C. Create global variables for elements outside any class and access them directly

D. Declare elements with @FindBy decorators, initialize with PageFactory.init_elements, then use element methods

Solution

1. Step 1: Understand Page Factory best practice

   Page Factory groups elements in a class using locator tuples and initializes them with PageFactory.init_elements.

2. Step 2: Compare with other options

   Options B, C, and D do not use Page Factory pattern and lead to less maintainable code.

3. Final Answer:

   Declare elements with @FindBy decorators, initialize with PageFactory.init_elements, then use element methods -> Option D

4. Quick Check:

   Page Factory = locators + init_elements + class grouping [OK]

Hint: Use locators and init_elements to organize page elements [OK]

Common Mistakes:

• Skipping class and locators for elements
• Using driver calls directly in tests
• Not initializing elements with PageFactory