Base page class in Selenium Python - Test Execution Trace

Test Overview

This test opens a web page using a base page class, finds a button by its ID, clicks it, and verifies the page title changes as expected.

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
import unittest

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

    def find_element(self, locator):
        return WebDriverWait(self.driver, 10).until(EC.presence_of_element_located(locator))

    def click(self, locator):
        element = self.find_element(locator)
        element.click()

class TestHomePage(unittest.TestCase):
    def setUp(self):
        self.driver = webdriver.Chrome()
        self.base_page = BasePage(self.driver)

    def test_click_button_changes_title(self):
        self.driver.get("https://example.com")
        button_locator = (By.ID, "start-button")
        self.base_page.click(button_locator)
        WebDriverWait(self.driver, 10).until(EC.title_is("Started Page"))
        self.assertEqual(self.driver.title, "Started Page")

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

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

Execution Trace - 7 Steps

Step	Action	System State	Assertion	Result
1	Test starts and WebDriver Chrome instance is created	Browser window opens, ready to navigate	—	PASS
2	Browser navigates to https://example.com	Page loads with a button having ID 'start-button'	—	PASS
3	BasePage finds element with ID 'start-button' using WebDriverWait	Button element is present and visible	Element presence verified by WebDriverWait	PASS
4	BasePage clicks the 'start-button'	Button is clicked, page starts navigation or changes	—	PASS
5	Wait until page title changes to 'Started Page'	Page title updates to 'Started Page'	Title is exactly 'Started Page'	PASS
6	Assert page title equals 'Started Page'	Page title is 'Started Page'	assertEqual passes confirming title	PASS
7	Test ends and browser closes	Browser window closes	—	PASS

Failure Scenario

Failing Condition: Button with ID 'start-button' is not found on the page

Execution Trace Quiz - 3 Questions

What does the BasePage class method 'find_element' do?

A Waits up to 10 seconds for an element to be present and returns it

B Clicks on an element immediately without waiting

C Navigates the browser to a URL

D Closes the browser window

Key Result

Using a base page class with reusable methods like 'find_element' and 'click' helps keep test code clean and easy to maintain.

Practice

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

easy

A. To group common web page actions and locators for reuse

B. To store test data for different test cases

C. To define the browser settings and capabilities

D. To generate test reports automatically

Solution

1. Step 1: Understand the role of BasePage

   The BasePage class is designed to hold common actions and locators shared by multiple page classes.

2. Step 2: Compare with other options

   Storing test data, browser settings, or generating reports are not responsibilities of BasePage.

3. Final Answer:

   To group common web page actions and locators for reuse -> Option A

4. Quick Check:

   BasePage groups common actions [OK]

Hint: BasePage holds shared page methods and locators [OK]

Common Mistakes:

• Confusing BasePage with test data storage
• Thinking BasePage manages browser setup
• Assuming BasePage creates reports

2. Which of the following is the correct way to define a locator tuple in a BasePage class?

easy

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

B. submit_button = ['id', 'submit']

C. submit_button = {'id': 'submit'}

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

Solution

1. Step 1: Recall locator tuple syntax

   Locator tuples use the format (By.<METHOD>, 'value'), e.g., (By.ID, 'submit').

2. Step 2: Check each option

   submit_button = (By.ID, 'submit') matches the tuple format. The other options use wrong data structures or invalid syntax.

3. Final Answer:

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

4. Quick Check:

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

Hint: Locator tuples always use parentheses and By constants [OK]

Common Mistakes:

• Using lists or dicts instead of tuples for locators
• Calling By.ID as a function
• Missing parentheses around locator tuple

3. Given this BasePage method, what will page.get_title() return if the browser's current page title is "Welcome Page"?

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

    def get_title(self):
        return self.driver.title

page = BasePage(driver)

medium

A. An error because get_title has no return

B. self.driver

C. None

D. "Welcome Page"

Solution

1. Step 1: Understand get_title method

   The method returns self.driver.title, which is the current page title string.

2. Step 2: Check given title

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

3. Final Answer:

   "Welcome Page" -> Option D

4. Quick Check:

   get_title returns driver.title = "Welcome Page" [OK]

Hint: get_title returns driver.title string [OK]

Common Mistakes:

• Thinking it returns the driver object
• Assuming no return means None
• Confusing method with attribute

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

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

    def click_element(locator):
        element = self.driver.find_element(*locator)
        element.click()

medium

A. Using find_element instead of find_elements

B. Missing 'self' parameter in click_element method

C. Locator should be a string, not a tuple

D. element.click() should be element.click

Solution

1. Step 1: Check method parameters

   Instance methods must have 'self' as the first parameter. Here, click_element lacks 'self'.

2. Step 2: Understand impact

   Without 'self', calling click_element will cause a TypeError because 'self.driver' is undefined.

3. Final Answer:

   Missing 'self' parameter in click_element method -> Option B

4. Quick Check:

   Instance methods need 'self' first [OK]

Hint: Always include 'self' as first method parameter [OK]

Common Mistakes:

• Forgetting 'self' in instance methods
• Confusing find_element with find_elements
• Misunderstanding locator types
• Using method call without parentheses

5. You want to create a BasePage method is_element_visible that returns True if an element is visible and False if not, without raising exceptions. Which is the best way to implement it?

hard

A. Use driver.page_source to search for element HTML string

B. Call find_element and return True without exception handling

C. Use try-except to catch NoSuchElementException and return False if caught

D. Use find_elements and check if list length is greater than zero

Solution

1. Step 1: Understand element visibility check

   Using find_element raises NoSuchElementException if element not found, so we must handle it.

2. Step 2: Use try-except for safe check

   Try to find element and check is_displayed(). If exception occurs, return False safely.

3. Final Answer:

   Use try-except to catch NoSuchElementException and return False if caught -> Option C

4. Quick Check:

   Try-except handles missing element safely [OK]

Hint: Wrap find_element in try-except to avoid exceptions [OK]

Common Mistakes:

• Not handling exceptions causing test failure
• Assuming find_elements always returns visible elements
• Searching page_source is unreliable and slow