1. Code Documentation — JSDoc Comments

JSDoc comments explain what code does. Heist.exe examples:

From Guard.js:

Code Runner Challenge

Unit Testing — Gem.collect()

View IPYNB Source 
/**
 * Reverse velocity when guard hits canvas edge to create bounce effect
 */
stayWithinCanvas() {
    if (this.position.y < 0) {
        this.velocity.y *= -1;  // Bounce at top
    }
}
Lines: 1 Characters: 0
Output
Click "Run" in code control panel to see output ...

From Gem.js:

Code Runner Challenge

API Error Handling — Fetch with try/catch and response.ok

View IPYNB Source 
/**
 * Marks gem as permanently collected to prevent double-collection
 */
collect() {
    if (this.permanentlyCollected) return;
    this.permanentlyCollected = true;
    gameEnv.stats.coinsCollected += this.value;
}
Lines: 1 Characters: 0
Output
Click "Run" in code control panel to see output ...

Target: > 10% comment density — 1 line of comments per ~10 lines of code.

%%js
//CODE_RUNNER: Unit Testing — Gem.collect()

const gameEnv = { stats: { coinsCollected: 0 } };

const gem = {
  value: 5,
  permanentlyCollected: false,
  collect() {
    if (this.permanentlyCollected) return;  // Block double-collection
    this.permanentlyCollected = true;
    gameEnv.stats.coinsCollected += this.value;
  }
};

// Test: collect once, then try again
gem.collect();
console.assert(gameEnv.stats.coinsCollected === 5, "FAIL: score should be 5");

gem.collect();
console.assert(gameEnv.stats.coinsCollected === 5, "FAIL: score should stay 5, not 10");

console.log("✅ Unit tests passed! Score:", gameEnv.stats.coinsCollected);

2. Integration Testing — Guard + Player Collision

Integration tests verify two systems work together. In Heist, test that Guard collision: detects player → runs handleCollisionEvent → destroys player → blocks re-collision.

From Guard.js:

if (!this.playerDestroyed && this.collisionChecks()) {
    this.handleCollisionEvent();  // Only fires once due to playerDestroyed flag
    player.destroy();
    this.playerDestroyed = true;
}

3. State Verification — Heist Game Stats

After collecting gems, verify the game state updated:

// After collecting 2 gems (5 points each):
console.assert(gameEnv.stats.coinsCollected === 10, "Should have 10 coins");
console.assert(gem1.permanentlyCollected === true, "gem1 should be locked");
console.assert(gem2.permanentlyCollected === true, "gem2 should be locked");

// Double-collection should fail:
gem1.collect();
console.assert(gameEnv.stats.coinsCollected === 10, "Still 10, not 15");

4. Boundary Testing — Guard Canvas Edges

Test Guard behavior at canvas edges:

// Bottom edge: should bounce
guard.position.y = gameEnv.innerHeight;
guard.stayWithinCanvas();
console.assert(guard.velocity.y < 0, "Should reverse at bottom");

// Top edge: should bounce
guard.position.y = 0;
guard.stayWithinCanvas();
console.assert(guard.velocity.y > 0, "Should reverse at top");

%%js
//CODE_RUNNER: API Error Handling — Fetch with try/catch and response.ok

async function testFetch(url, label) {
    try {
        const response = await fetch(url);
        if (!response.ok) throw new Error(`HTTP ${response.status}`);
        console.log(`[${label}] ✓ Success`);
    } catch (error) {
        console.error(`[${label}] ✗ Error:`, error.message);
    }
}

// Test bad URL
await testFetch('https://official-joke-api.appspot.com/jokes/invalid', 'Bad endpoint');

// Test good URL
await testFetch('https://official-joke-api.appspot.com/random_joke', 'Good endpoint');

console.log('✅ Both paths tested');

Summary — Testing Checklist for Heist.exe

Based on CS111 Testing & Verification Documentation:

Test Type What to Verify Heist.exe Example Tool
Unit Testing Single method with known inputs Gem.collect() — collects once, blocks double-collection Code runner
Integration Testing Two systems work together Guard + Player — collision triggers destroy sequence Code runner
State Verification Runtime values match expected gameEnv.stats.coinsCollected === 10 after 2 gems DevTools Console
Boundary Testing Edge cases at limits Guard at top/bottom/left/right canvas edges Code runner
API Error Handling Both success and failure paths iTunes music fetch with try/catch + !response.ok Code runner

The goal: Test the parts that break in interesting ways. In Heist.exe, that’s one-time events (gem collection, collision) and external dependencies (iTunes API for music).