Unit testing in Testing Fundamentals - Test Execution Trace

Test Overview

This test checks a simple function that adds two numbers. It verifies that the function returns the correct sum.

Test Code - unittest

Testing Fundamentals

def add(a, b):
    return a + b

import unittest

class TestAddFunction(unittest.TestCase):
    def test_add_two_positive_numbers(self):
        result = add(3, 5)
        self.assertEqual(result, 8)

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

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Test starts	Python unittest framework initializes the test runner	-	PASS
2	Calls add(3, 5)	Function add is executed with inputs 3 and 5	-	PASS
3	Receives result 8 from add function	Result stored in variable 'result'	-	PASS
4	Checks if result equals 8 using assertEqual	Assertion compares expected 8 with actual 8	self.assertEqual(result, 8)	PASS
5	Test completes successfully	Test runner reports test passed	-	PASS

Failure Scenario

Failing Condition: The add function returns a wrong sum, e.g., 7 instead of 8

Execution Trace Quiz - 3 Questions

What does the test verify?

A The add function multiplies two numbers

B The add function returns the correct sum of two numbers

C The add function returns a string

D The add function throws an error

Key Result

Unit tests should check one small piece of code and verify its output with clear assertions to catch errors early.