Pair Testing on Login Functionality

Preconditions (3)

Step 1: Tester A enters 'user@example.com' in the email field

Step 2: Tester A enters 'Password123' in the password field

Step 3: Tester A clicks the Login button

Step 4: Tester B observes the behavior and notes any issues

Step 5: Both testers discuss and verify if the login was successful

Step 6: Repeat the above steps for invalid email format 'userexample.com' and verify error message

Step 7: Repeat the above steps for empty password field and verify error message

Step 8: Repeat the above steps for correct email and wrong password and verify error message

✅ Expected Result: Login succeeds only with valid credentials; appropriate error messages appear for invalid inputs; both testers agree on the test outcomes

Automation Requirements - Selenium with Python

Assertions Needed:

Verify URL changes to dashboard after successful login

Verify error message is displayed for invalid email format

Verify error message is displayed for empty password

Verify error message is displayed for wrong password

Best Practices:

Use explicit waits to handle page loading

Use clear and maintainable locators (By.ID, By.NAME)

Separate test data from test logic

Use assertions to validate expected outcomes

Write clean and readable code with comments

Automated Solution

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 TestLogin(unittest.TestCase):
    def setUp(self):
        self.driver = webdriver.Chrome()
        self.driver.get('https://example.com/login')
        self.wait = WebDriverWait(self.driver, 10)

    def login(self, email, password):
        email_field = self.wait.until(EC.presence_of_element_located((By.ID, 'email')))
        password_field = self.driver.find_element(By.ID, 'password')
        login_button = self.driver.find_element(By.ID, 'loginBtn')

        email_field.clear()
        email_field.send_keys(email)
        password_field.clear()
        password_field.send_keys(password)
        login_button.click()

    def test_valid_login(self):
        self.login('user@example.com', 'Password123')
        self.wait.until(EC.url_contains('/dashboard'))
        self.assertIn('/dashboard', self.driver.current_url)

    def test_invalid_email_format(self):
        self.login('userexample.com', 'Password123')
        error = self.wait.until(EC.visibility_of_element_located((By.ID, 'emailError')))
        self.assertEqual(error.text, 'Please enter a valid email address.')

    def test_empty_password(self):
        self.login('user@example.com', '')
        error = self.wait.until(EC.visibility_of_element_located((By.ID, 'passwordError')))
        self.assertEqual(error.text, 'Password cannot be empty.')

    def test_wrong_password(self):
        self.login('user@example.com', 'WrongPass')
        error = self.wait.until(EC.visibility_of_element_located((By.ID, 'loginError')))
        self.assertEqual(error.text, 'Incorrect email or password.')

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

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

This test script uses Selenium with Python's unittest framework to automate the login tests.

setUp: Opens the browser and navigates to the login page before each test.

login method: Enters email and password, then clicks login.

test_valid_login: Checks that after valid login, URL contains '/dashboard'.

test_invalid_email_format: Checks error message for invalid email format.

test_empty_password: Checks error message when password is empty.

test_wrong_password: Checks error message for wrong password.

tearDown: Closes the browser after each test.

Explicit waits ensure elements are ready before interaction. Assertions verify expected results. Locators use IDs for clarity and maintainability.

Common Mistakes - 4 Pitfalls

Using time.sleep() instead of explicit waits

Hardcoding test data inside test methods

Using brittle locators like absolute XPath

Not closing the browser after tests

Bonus Challenge

Now add data-driven testing with 3 different sets of login credentials (valid, invalid email, wrong password).

Show Hint