Why security testing protects users in Testing Fundamentals - Test Execution Impact

Test Overview

This test checks if the login page properly blocks access when wrong credentials are used, protecting user accounts from unauthorized access.

Test Code - Selenium with unittest

Testing Fundamentals

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

    def test_invalid_login_blocks_access(self):
        driver = self.driver
        # Wait for username field
        WebDriverWait(driver, 10).until(EC.presence_of_element_located((By.ID, 'username')))
        username_input = driver.find_element(By.ID, 'username')
        password_input = driver.find_element(By.ID, 'password')
        login_button = driver.find_element(By.ID, 'login-btn')

        # Enter invalid credentials
        username_input.send_keys('wronguser')
        password_input.send_keys('wrongpass')
        login_button.click()

        # Wait for error message
        error_message = WebDriverWait(driver, 10).until(
            EC.visibility_of_element_located((By.ID, 'error-msg'))
        )

        # Verify error message text
        self.assertEqual(error_message.text, 'Invalid username or password.')

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

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

Execution Trace - 8 Steps

Step	Action	System State	Assertion	Result
1	Test starts and opens Chrome browser	Browser window opens at 'https://example.com/login' showing login form with username, password fields and login button	-	PASS
2	Waits for username input field to be present	Login page fully loaded with input fields visible	Username input field is present	PASS
3	Finds username, password fields and login button	All required elements located on the page	Elements found by ID selectors	PASS
4	Enters invalid username and password	Input fields filled with 'wronguser' and 'wrongpass'	-	PASS
5	Clicks login button	Login form submitted, page processes login	-	PASS
6	Waits for error message to appear	Error message element visible with text 'Invalid username or password.'	Error message is visible	PASS
7	Checks error message text matches expected	Error message text is exactly 'Invalid username or password.'	Error message text equals expected string	PASS
8	Test ends and browser closes	Browser window closed	-	PASS

Failure Scenario

Failing Condition: If the error message does not appear or text is incorrect after invalid login attempt

Execution Trace Quiz - 3 Questions

What does the test verify after clicking the login button with wrong credentials?

A The password field is cleared automatically

B The user is redirected to the homepage

C An error message appears saying 'Invalid username or password.'

D The login button becomes disabled

Key Result

Security testing verifies that the system properly blocks unauthorized access by checking error messages on invalid login attempts, protecting user accounts from misuse.