Code review exercises provide immediate signal on how candidates inspect code for bugs, edge cases, and architectural flaws. Here are 15 realistic code review interview scenarios complete with what interviewers should look for.
Scenario 1: Database N+1 Query Anti-Pattern
javascriptPairlet Snippet
// Flawed Pull Request:
async function getUsersWithOrders(userIds) {
const users = [];
for (const id of userIds) {
const user = await db.query('SELECT * FROM users WHERE id = $1', [id]);
const orders = await db.query('SELECT * FROM orders WHERE user_id = $1', [id]);
users.push({ ...user, orders });
}
return users;
}
```
- **What to look for**: Candidate identifies N+1 database roundtrips and refactors using SQL `IN (...)` clauses or batch JOIN queries.Scenario 2: Swallowed Async Exceptions
javascriptPairlet Snippet
// Flawed Pull Request:
async function processPayment(payment) {
try {
await stripe.charges.create(payment);
await auditLogger.log(payment.id);
} catch (err) {
console.log("Something went wrong");
return true; // Returns success despite failure!
}
}
```
- **What to look for**: Candidate catches the silent error swallowing and false positive return value.Scenario 3: Node.js Memory Leak via Global Listeners
- •*Practice Node.js Memory Leak on Pairlet.*
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Frequently Asked Questions
What categories of bugs work best in code review exercises?
Database performance (N+1 queries), Async error swallowing, Authorization checking bypasses, Node.js memory leaks, and Unrestricted Promise concurrency.
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