Code Review – 100+ Lab Exercises (Basic, Intermediate, Advanced)

🔰 Basic Level (30+ Exercises)

 

Goal: Build fundamental code review skills, understand syntax, readability, and simple refactorings.

 

Code Comprehension

  • Review and summarize what a simple function does (in Python, JavaScript, or Java).

  • Spot unused variables or unreachable code.

  • Identify hardcoded values and suggest constant usage.

  • Suggest better naming conventions for variables and functions.

  • Explain the control flow of basic algorithms (e.g., sorting, searching).

Style & Readability

  • Enforce consistent indentation and formatting (tabs vs spaces).

  • Ensure consistent casing (camelCase, PascalCase, snake_case).

  • Check alignment with style guides (e.g., PEP8, Google Java Style).

  • Review HTML/CSS for structure and semantic tag usage.

  • Identify comments that need clarification or removal.

Basic Best Practices

  • Spot functions doing too many things (violating SRP).

  • Suggest converting a loop into a more readable map/filter.

  • Replace magic numbers with named constants.

  • Remove redundant else blocks after return.

  • Identify off-by-one errors in loops.

 

🚀 Intermediate Level (40+ Exercises)

 

Goal: Review code for maintainability, performance, and adherence to design principles.

 

Code Efficiency & Complexity

  • Analyze Big-O time/space complexity of a function.

  • Refactor nested loops into more efficient solutions.

  • Identify bottlenecks in recursive solutions.

  • Suggest caching/memoization where applicable.

  • Recommend use of built-in libraries or idiomatic syntax.

Design Patterns & Architecture

  • Identify violations of SOLID principles.

  • Review factory and singleton pattern implementations.

  • Check for tight coupling and recommend dependency injection.

  • Suggest breaking down monolithic classes into modules.

  • Enforce separation of concerns (MVC, MVVM, etc.).

Testability & Unit Tests

  • Review test cases for edge conditions.

  • Ensure meaningful assertions in tests.

  • Suggest mocking/stubbing over external API calls.

  • Spot untested branches of code.

  • Recommend parameterized tests and coverage tools.

Version Control Hygiene

  • Identify oversized pull requests and suggest splitting.

  • Review commit messages for clarity and atomicity.

  • Ensure feature branches follow naming conventions.

  • Spot unwanted debug logs or commented code.

  • Enforce .gitignore compliance.

 

🧠 Advanced Level (40+ Exercises)

 

Goal: Master code review across systems, security, scalability, and mentor others in the review process.

 

Security & Compliance

  • Detect SQL injection vulnerabilities in raw queries.

  • Review code for XSS, CSRF vulnerabilities in web apps.

  • Validate authentication and token management flows.

  • Check for usage of insecure hashing/encryption (e.g., MD5, SHA-1).

  • Review 3rd-party library usage and CVE reports.

Concurrency & Scalability

  • Review thread-safe implementation using locks, mutexes, or channels.

  • Check async/await logic and race conditions.

  • Validate scalability of microservices in distributed systems.

  • Analyze rate limiting and load balancing logic.

  • Review circuit breakers and retry patterns.

API & Integration

  • Review RESTful API for status code accuracy.

  • Validate GraphQL resolver design for N+1 query issues.

  • Review API contract versioning and backward compatibility.

  • Analyze response time optimization (pagination, compression).

  • Ensure robust error handling and logging in API endpoints.

Mentorship & Collaboration

  • Write constructive code review comments.

  • Conduct mock live code review sessions.

  • Mentor junior developers through example-based feedback.

  • Drive cultural shift toward collaborative reviews.

  • Champion best practices via review templates/checklists.

Capstone Review Projects

 

  • Perform a full-stack application codebase review.

  • Review a microservice end-to-end: infra, logic, and tests.

  • Evaluate a monorepo for modularization and refactoring.

  • Run a security audit on a payment/finance module.

  • Simulate a review for an open-source pull request.

 

✅ Tools & Platforms

 

  • Linting & Formatters: ESLint, Prettier, Black, Flake8

  • Code Review Platforms: GitHub, GitLab, Bitbucket, Gerrit

  • CI Tools: GitHub Actions, CircleCI, Jenkins

  • Testing Frameworks: Jest, PyTest, JUnit, Mocha

  • Security Tools: SonarQube, Snyk, CodeQL

  • Coverage Tools: Istanbul, Codecov, JaCoCo

  • Architecture Review Aids: PlantUML, Mermaid.js, Lucidchart

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