Find element by class name in Selenium Python - Test Execution Trace

Test Overview

This test opens a web page, finds an element using its class name, and verifies that the element's text matches the expected value.

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 TestFindByClassName(unittest.TestCase):
    def setUp(self):
        self.driver = webdriver.Chrome()
        self.driver.get('https://example.com')

    def test_find_element_by_class_name(self):
        driver = self.driver
        wait = WebDriverWait(driver, 10)
        element = wait.until(EC.presence_of_element_located((By.CLASS_NAME, 'example')))
        self.assertEqual(element.text, 'Example Domain')

    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	Chrome browser window is open, ready to load the page	—	PASS
2	Browser navigates to 'https://example.com'	Page 'https://example.com' is loaded and visible	—	PASS
3	Waits up to 10 seconds for element with class name 'example' to be present	Element with class 'example' is found on the page	Element presence verified	PASS
4	Checks that the element's text equals 'Example Domain'	Element text is 'Example Domain'	Assert element.text == 'Example Domain'	PASS
5	Browser closes and test ends	Browser window closed	—	PASS

Failure Scenario

Failing Condition: Element with class name 'example' is not found within 10 seconds

Execution Trace Quiz - 3 Questions

What does the test wait for before proceeding?

A Page title to be 'Example Domain'

B Presence of element with class name 'example'

C Element with id 'example-class' to be clickable

D Browser URL to change

Key Result

Always use explicit waits like WebDriverWait with expected conditions to reliably find elements by class name before interacting or asserting.

Practice

1. What does the Selenium method find_element(By.CLASS_NAME, "example") do?

easy

A. Finds elements by their ID "example".

B. Finds all elements with the class name "example" on the webpage.

C. Finds elements by their tag name "example".

D. Finds the first element with the class name "example" on the webpage.

Solution

1. Step 1: Understand the method purpose

   The method find_element locates a single element on the page.

2. Step 2: Identify the locator type

   Using By.CLASS_NAME means it looks for the first element with the given class name.

3. Final Answer:

   Finds the first element with the class name "example" on the webpage. -> Option D

4. Quick Check:

   find_element + CLASS_NAME = first matching element [OK]

Hint: find_element with CLASS_NAME finds only the first matching element [OK]

Common Mistakes:

• Confusing find_element with find_elements (plural)
• Using class name but expecting multiple elements
• Mixing class name with ID or tag name locators

2. Which of the following is the correct syntax to find an element by class name "btn-primary" using Selenium in Python?

easy

A. driver.find_element(By.CLASS_NAME, "btn-primary")

B. driver.find_element_by_class_name("btn-primary")

C. driver.find_element(By.CLASS, "btn-primary")

D. driver.find_element(By.CLASSNAME, "btn-primary")

Solution

1. Step 1: Recall the correct Selenium syntax

   In Selenium Python 4+, the recommended syntax is find_element(By.CLASS_NAME, "class").

2. Step 2: Check each option for correctness

   driver.find_element(By.CLASS_NAME, "btn-primary") uses the correct locator By.CLASS_NAME and method find_element. Others use deprecated or incorrect locators.

3. Final Answer:

   driver.find_element(By.CLASS_NAME, "btn-primary") -> Option A

4. Quick Check:

   Use By.CLASS_NAME with find_element [OK]

Hint: Use By.CLASS_NAME with find_element, not old deprecated methods [OK]

Common Mistakes:

• Using deprecated find_element_by_class_name method
• Wrong locator names like CLASS or CLASSNAME
• Missing quotes around class name string

3. Given the HTML snippet:

<div class="alert success">Success!</div>
<div class="alert error">Error!</div>

What text will this Selenium Python code print?

element = driver.find_element(By.CLASS_NAME, "alert")
print(element.text)

medium

A. "Success!"

B. "Error!"

C. "Success! Error!"

D. Throws NoSuchElementException

Solution

1. Step 1: Understand find_element behavior

   It finds the first element matching the class name "alert" in the HTML order.

2. Step 2: Identify the first matching element

   The first <div> with class "alert success" contains text "Success!".

3. Final Answer:

   "Success!" -> Option A

4. Quick Check:

   find_element returns first matching element's text [OK]

Hint: find_element returns first match only, so text is from first element [OK]

Common Mistakes:

• Assuming it returns all matching elements' text
• Confusing class names with multiple classes
• Expecting an error if multiple classes exist

4. What is wrong with this Selenium Python code snippet?

element = driver.find_element(By.CLASS_NAME, ".button")

medium

A. find_element should be find_elements to find class

B. Class name should not include the dot prefix "."

C. By.CLASS_NAME is not a valid locator

D. The class name must be uppercase

Solution

1. Step 1: Check the class name format

   When using By.CLASS_NAME, the class name should be given without any CSS selector symbols like ".".

2. Step 2: Identify the error in the code

   The code incorrectly includes a dot prefix ".button" which causes a failure to find the element.

3. Final Answer:

   Class name should not include the dot prefix "." -> Option B

4. Quick Check:

   Class name locator needs plain class name, no dot [OK]

Hint: Remove dot prefix when using By.CLASS_NAME locator [OK]

Common Mistakes:

• Adding dot prefix like CSS selectors to class name
• Using find_elements when only one element is needed
• Assuming class names must be uppercase

5. You want to click the first button with class "submit-btn" on a page. Which code snippet correctly finds and clicks it using Selenium Python?

hard

A. button = driver.find_elements(By.CLASS_NAME, "submit-btn")
button.click()

B. button = driver.find_element(By.ID, "submit-btn")
button.click()

C. button = driver.find_element(By.CLASS_NAME, "submit-btn")
button.click()

D. button = driver.find_element(By.CLASS_NAME, ".submit-btn")
button.click()

Solution

1. Step 1: Choose correct method to find single element by class

   Use find_element(By.CLASS_NAME, "submit-btn") to get the first matching element.

2. Step 2: Call click() on the found element

   After locating the element, call click() to perform the click action.

3. Final Answer:

   button = driver.find_element(By.CLASS_NAME, "submit-btn")\nbutton.click() -> Option C

4. Quick Check:

   find_element + CLASS_NAME + click() = correct usage [OK]

Hint: Use find_element with class name, then call click() on it [OK]

Common Mistakes:

• Using find_elements returns list, cannot call click() directly
• Using ID locator instead of class name
• Including dot prefix in class name