Function test

test/network/stack.test.js:14–24

(name, fn)

let failed = 0;

function test(name, fn) {
    try {
        fn();
        console.log(`✓ ${name}`);
        passed++;
    } catch (e) {
        console.log(`✗ ${name}`);
        console.log(`  Error: ${e.message}`);
        failed++;
    }
}

// Helper to create Ethernet frame
function createEthFrame(srcMac, dstMac, etherType, payload) {