Verify discount calculation using decision table

Preconditions (1)

Step 1: Enter purchase amount as 50

Step 2: Select customer type as 'Regular'

Step 3: Click Calculate Discount button

Step 4: Verify discount is 0

Step 5: Enter purchase amount as 150

Step 6: Select customer type as 'Regular'

Step 7: Click Calculate Discount button

Step 8: Verify discount is 10

Step 9: Enter purchase amount as 50

Step 10: Select customer type as 'Premium'

Step 11: Click Calculate Discount button

Step 12: Verify discount is 5

Step 13: Enter purchase amount as 150

Step 14: Select customer type as 'Premium'

Step 15: Click Calculate Discount button

Step 16: Verify discount is 20

✅ Expected Result: Discount is correctly calculated based on purchase amount and customer type according to the decision table rules.

Automation Requirements - Selenium with Python

Assertions Needed:

Verify discount value displayed matches expected discount for each input combination

Best Practices:

Use explicit waits to wait for elements

Use clear and maintainable locators (id or name preferred)

Separate test data from test logic

Use assertions from unittest or pytest

Structure code for readability

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 DiscountCalculatorTest(unittest.TestCase):
    def setUp(self):
        self.driver = webdriver.Chrome()
        self.driver.get('http://example.com/discount-calculator')
        self.wait = WebDriverWait(self.driver, 10)

    def test_discount_calculation(self):
        test_cases = [
            {'amount': '50', 'customer_type': 'Regular', 'expected_discount': '0'},
            {'amount': '150', 'customer_type': 'Regular', 'expected_discount': '10'},
            {'amount': '50', 'customer_type': 'Premium', 'expected_discount': '5'},
            {'amount': '150', 'customer_type': 'Premium', 'expected_discount': '20'}
        ]

        for case in test_cases:
            amount_input = self.wait.until(EC.presence_of_element_located((By.ID, 'purchaseAmount')))
            amount_input.clear()
            amount_input.send_keys(case['amount'])

            customer_select = self.wait.until(EC.presence_of_element_located((By.ID, 'customerType')))
            for option in customer_select.find_elements(By.TAG_NAME, 'option'):
                if option.text == case['customer_type']:
                    option.click()
                    break

            calculate_button = self.wait.until(EC.element_to_be_clickable((By.ID, 'calculateBtn')))
            calculate_button.click()

            discount_output = self.wait.until(EC.visibility_of_element_located((By.ID, 'discountValue')))
            self.assertEqual(discount_output.text, case['expected_discount'],
                             f"Discount for amount {case['amount']} and customer {case['customer_type']} should be {case['expected_discount']}")

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

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

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

In setUp, the browser opens the page and sets an explicit wait.

The test_discount_calculation method loops through all decision table cases. For each case, it:

Finds and fills the purchase amount input.
Selects the customer type from dropdown.
Clicks the calculate button.
Waits for the discount output to appear.
Asserts the displayed discount matches the expected value.

Explicit waits ensure elements are ready before interacting.

Locators use IDs for clarity and maintainability.

The test data is separated in a list for easy updates.

Finally, tearDown closes the browser after tests.

Common Mistakes - 4 Pitfalls

Using time.sleep() instead of explicit waits

Using brittle XPath locators with full paths

Hardcoding test data inside test steps

Not clearing input fields before sending keys

Bonus Challenge

Now add data-driven testing with 3 more different purchase amounts and customer types.

Show Hint