Verify that the software correctly identifies a simple bug in a calculator function

Preconditions (2)

Step 1: Open the calculator application

Step 2: Enter the number 2

Step 3: Press the addition (+) button

Step 4: Enter the number 2

Step 5: Press the equals (=) button

Step 6: Observe the result displayed

✅ Expected Result: The calculator displays the result as 4

Automation Requirements - unittest with Selenium WebDriver

Assertions Needed:

Verify the displayed result equals '4'

Best Practices:

Use explicit waits to wait for the result to appear

Use clear and maintainable locators (e.g., By.ID or By.CSS_SELECTOR)

Structure code with setup and teardown methods

Keep assertions simple and focused

Automated Solution

Testing Fundamentals

import unittest
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

class TestCalculatorAddition(unittest.TestCase):
    def setUp(self):
        self.driver = webdriver.Chrome()
        self.driver.get('http://localhost:8000/calculator')  # Example URL

    def test_addition(self):
        driver = self.driver
        wait = WebDriverWait(driver, 10)

        # Click number 2 button
        driver.find_element(By.ID, 'btn-2').click()
        # Click plus button
        driver.find_element(By.ID, 'btn-plus').click()
        # Click number 2 button again
        driver.find_element(By.ID, 'btn-2').click()
        # Click equals button
        driver.find_element(By.ID, 'btn-equals').click()

        # Wait for result to appear
        result_element = wait.until(EC.visibility_of_element_located((By.ID, 'result')))

        # Assert the result is '4'
        self.assertEqual(result_element.text, '4')

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

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

This test script uses Python's unittest framework with Selenium WebDriver to automate the calculator addition test.

setUp: Opens the browser and navigates to the calculator page.

test_addition: Clicks buttons for '2', '+', '2', and '=' in order. Then waits explicitly for the result element to appear. Finally, it asserts that the displayed result text is '4'.

tearDown: Closes the browser after the test finishes.

This structure keeps the test clear, waits properly for UI updates, and uses maintainable locators by ID.

Common Mistakes - 3 Pitfalls

Using time.sleep() instead of explicit waits

Using brittle XPath locators like absolute paths

Not closing the browser after tests

Bonus Challenge

Now add data-driven testing with 3 different addition inputs and expected results

Show Hint