Unit Testing, Integration Testing, Memory Leaks & Bug Fixing

Explanation

Testing verifies that the software satisfies all initial functional requirements without regressions or security vulnerabilities. In C++, dynamic memory leaks degrade host OS performance over long execution runs, making systematic lifecycle verification a critical project deliverable.

Key points

• Integration Testing: Verifying correct interaction between UI menus, business logic validation, and file persistence storage.
• Boundary Value Analysis: Testing inputs at extreme boundaries (e.g., 0 balance, max array size, end-of-file conditions).
• Memory Leak Detection: Ensuring every heap allocation via new or new[] is paired with an equivalent delete or delete[].
• Defensive Programming: Adding assertions (assert.h) and structured try-catch exception blocks.

Example

Code examples

// Defensive Unit Testing Test-Harness Pattern in C++
#include <iostream>
#include <cassert>
using namespace std;

class Calculator {
public:
    static int divide(int a, int b) {
        if (b == 0) throw invalid_argument("Zero division");
        return a / b;
    }
};

void runUnitTests() {
    assert(Calculator::divide(10, 2) == 5);
    assert(Calculator::divide(-6, 2) == -3);
    try {
        Calculator::divide(5, 0);
        assert(false); // Should not reach here!
    } catch (const invalid_argument&) {
        // Exception expected and successfully caught!
    }
    cout << "All automated unit tests passed cleanly!" << endl;
}

Exam questions

• [7 Marks] Differentiate between unit testing and integration testing. Describe test cases for a bank withdrawal function.
• [7 Marks] Explain common memory management errors in C++ (dangling pointers, double-free, memory leaks) and their remedies.