Unit Testing

#include <iostream>
using namespace std;

// === A tiny test harness (so these tests RUN in the editor) ===
// Real projects use a framework; this 6-line helper does the same job
// for learning: it checks a condition and prints a pass/fail line.
int passed = 0, failed = 0;
void check(bool condition, const string& testName) {
    if (condition) { cout << "  [PASS] " << testName << "\n"; passed++; }
    else           { cout << "  [FAIL] " << testName << "\n"; failed++; }
}

// === The code under
...

#include <iostream>
using namespace std;

// Same tiny harness — fill in the blanks below, then press "Try it Yourself".
int passed = 0, failed = 0;
void check(bool condition, const string& testName) {
    if (condition) { cout << "  [PASS] " << testName << "\n"; passed++; }
    else           { cout << "  [FAIL] " << testName << "\n"; failed++; }
}

// Code under test:
int square(int n) { return n * n; }

int main() {
    // 🎯 YOUR TURN — replace each ___ then run it.

    // 1) ARRANGE + ACT:
...

#include <iostream>
#include <stdexcept>
using namespace std;

int passed = 0, failed = 0;
void check(bool condition, const string& testName) {
    if (condition) { cout << "  [PASS] " << testName << "\n"; passed++; }
    else           { cout << "  [FAIL] " << testName << "\n"; failed++; }
}

// Code under test: integer division that refuses divide-by-zero.
int safeDivide(int a, int b) {
    if (b == 0) throw invalid_argument("divide by zero");
    return a / b;
}

int main() {
    // Good test
...

#include <iostream>
using namespace std;

int passed = 0, failed = 0;
void check(bool condition, const string& testName) {
    if (condition) { cout << "  [PASS] " << testName << "\n"; passed++; }
    else           { cout << "  [FAIL] " << testName << "\n"; failed++; }
}

// Code under test: clamp keeps a value inside [low, high].
int clamp(int value, int low, int high) {
    if (value < low) return low;
    if (value > high) return high;
    return value;
}

int main() {
    // 🎯 YOUR TURN — 
...

// === GoogleTest (gtest) — how the pros write the SAME tests ===
// You don't run this here (it needs the gtest library linked in),
// but notice it is the AAA pattern with nicer macros.
#include <gtest/gtest.h>

int add(int a, int b) { return a + b; }

// TEST(TestSuiteName, TestName) defines one test case.
TEST(AddTest, ReturnsSumOfTwoPositives) {
    EXPECT_EQ(add(2, 3), 5);     // EXPECT_* keeps going if it fails
}

TEST(AddTest, HandlesNegatives) {
    EXPECT_EQ(add(-1, 1), 0);
    ASSERT_
...

// === Catch2 — a popular header-only framework ===
// Same idea, even less boilerplate. Run here? No — it needs Catch2 linked.
#define CATCH_CONFIG_MAIN          // generates main() for you
#include <catch2/catch_all.hpp>

int add(int a, int b) { return a + b; }

// TEST_CASE("description", "[tag]") names the test in plain English.
TEST_CASE("add returns the sum", "[math]") {
    REQUIRE(add(2, 3) == 5);      // REQUIRE stops the test on failure
    CHECK(add(0, 0) == 0);        // CHECK report
...