Cost of bugs at different stages in Testing Fundamentals - Test Execution Trace

Test Overview

This test simulates finding a bug at different stages of software development and verifies the cost impact at each stage.

It checks that bugs found earlier cost less to fix than those found later.

Test Code - unittest

Testing Fundamentals

import unittest

class TestBugCost(unittest.TestCase):
    def cost_of_bug(self, stage):
        costs = {
            'requirements': 100,
            'design': 500,
            'coding': 1000,
            'testing': 5000,
            'production': 10000
        }
        return costs.get(stage, 0)

    def test_bug_costs(self):
        # Bug found at requirements stage
        cost_req = self.cost_of_bug('requirements')
        self.assertEqual(cost_req, 100)

        # Bug found at design stage
        cost_des = self.cost_of_bug('design')
        self.assertEqual(cost_des, 500)

        # Bug found at coding stage
        cost_code = self.cost_of_bug('coding')
        self.assertEqual(cost_code, 1000)

        # Bug found at testing stage
        cost_test = self.cost_of_bug('testing')
        self.assertEqual(cost_test, 5000)

        # Bug found at production stage
        cost_prod = self.cost_of_bug('production')
        self.assertEqual(cost_prod, 10000)

        # Verify costs increase with later stages
        self.assertTrue(cost_req < cost_des < cost_code < cost_test < cost_prod)

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

Execution Trace - 8 Steps

Step	Action	System State	Assertion	Result
1	Test starts	Test framework initialized, test class loaded	-	PASS
2	Calls cost_of_bug('requirements')	Returns 100	assertEqual(100, 100)	PASS
3	Calls cost_of_bug('design')	Returns 500	assertEqual(500, 500)	PASS
4	Calls cost_of_bug('coding')	Returns 1000	assertEqual(1000, 1000)	PASS
5	Calls cost_of_bug('testing')	Returns 5000	assertEqual(5000, 5000)	PASS
6	Calls cost_of_bug('production')	Returns 10000	assertEqual(10000, 10000)	PASS
7	Checks costs increase with later stages	Values: 100 < 500 < 1000 < 5000 < 10000	assertTrue(cost_req < cost_des < cost_code < cost_test < cost_prod)	PASS
8	Test ends	All assertions passed	-	PASS

Failure Scenario

Failing Condition: If cost values do not match expected or order is incorrect

Execution Trace Quiz - 3 Questions

What does the test verify about bug costs?

A Bugs cost less to fix the later they are found

B Bugs cost the same at all stages

C Bugs cost more to fix the later they are found

D Bug cost is random

Key Result

Testing cost impact at different stages helps teams understand why early bug detection saves money and effort.