Why systematic techniques improve coverage in Testing Fundamentals - Test Execution Impact

Test Overview

This test simulates applying a systematic testing technique to ensure all parts of a simple calculator app are tested. It verifies that each function (add, subtract, multiply, divide) is covered by at least one test case, improving overall test coverage.

Test Code - unittest

Testing Fundamentals

import unittest

class Calculator:
    def add(self, a, b):
        return a + b
    def subtract(self, a, b):
        return a - b
    def multiply(self, a, b):
        return a * b
    def divide(self, a, b):
        if b == 0:
            raise ValueError("Cannot divide by zero")
        return a / b

class TestCalculator(unittest.TestCase):
    def setUp(self):
        self.calc = Calculator()

    def test_add(self):
        self.assertEqual(self.calc.add(2, 3), 5)

    def test_subtract(self):
        self.assertEqual(self.calc.subtract(5, 3), 2)

    def test_multiply(self):
        self.assertEqual(self.calc.multiply(4, 3), 12)

    def test_divide(self):
        self.assertEqual(self.calc.divide(10, 2), 5)

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

Execution Trace - 6 Steps

Step	Action	System State	Assertion	Result
1	Test starts	Test runner initializes the Calculator and TestCalculator classes	-	PASS
2	Runs test_add method	Calculator instance ready, inputs 2 and 3	Check if add(2, 3) == 5	PASS
3	Runs test_subtract method	Calculator instance ready, inputs 5 and 3	Check if subtract(5, 3) == 2	PASS
4	Runs test_multiply method	Calculator instance ready, inputs 4 and 3	Check if multiply(4, 3) == 12	PASS
5	Runs test_divide method	Calculator instance ready, inputs 10 and 2	Check if divide(10, 2) == 5	PASS
6	Test ends with all methods covered	All calculator functions tested once	Verify all functions have test coverage	PASS

Failure Scenario

Failing Condition: If any calculator function is not tested, e.g., test_divide method missing

Execution Trace Quiz - 3 Questions

What does the test_add method verify?

A That subtracting 2 from 3 returns 1

B That adding 2 and 3 returns 5

C That multiplying 2 and 3 returns 6

D That dividing 2 by 3 returns 0.66

Key Result

Using systematic techniques like writing separate tests for each function ensures all parts of the software are checked, improving test coverage and reducing the chance of missing bugs.