Black-box vs white-box testing in Testing Fundamentals - Test Execution Compared

Test Overview

This test compares black-box and white-box testing approaches by verifying a simple login function works correctly without and with knowledge of the code.

Test Code - unittest

Testing Fundamentals

import unittest

# Simple login function to test

def login(username, password):
    # White-box knowledge: valid credentials are 'user' and 'pass123'
    if username == 'user' and password == 'pass123':
        return True
    else:
        return False

class TestLogin(unittest.TestCase):
    def test_black_box_valid(self):
        # Black-box test: only input/output knowledge
        self.assertTrue(login('user', 'pass123'))

    def test_black_box_invalid(self):
        self.assertFalse(login('user', 'wrongpass'))

    def test_white_box_edge(self):
        # White-box test: testing edge case knowing code
        self.assertFalse(login('', ''))

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

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Test suite starts	Test runner initialized, login function loaded	-	PASS
2	Run test_black_box_valid: call login('user', 'pass123')	Function receives valid credentials	Assert login returns True	PASS
3	Run test_black_box_invalid: call login('user', 'wrongpass')	Function receives invalid password	Assert login returns False	PASS
4	Run test_white_box_edge: call login('', '')	Function receives empty strings as input	Assert login returns False	PASS
5	Test suite ends	All tests executed	All assertions passed	PASS

Failure Scenario

Failing Condition: login function incorrectly returns True for invalid credentials

Execution Trace Quiz - 3 Questions

Which test uses only input and output knowledge without looking at the code?

A Unit testing

B White-box testing

C Black-box testing

D Integration testing

Key Result

Black-box testing focuses on inputs and outputs without code knowledge, while white-box testing uses internal code knowledge to design tests, especially for edge cases.