Code review checklist for LLD - Architecture Diagram

System Overview - Code review checklist for LLD

This system provides a structured checklist to guide code reviews specifically for Low-Level Design (LLD) documents and implementations. It ensures that code adheres to design principles, is maintainable, and meets quality standards before integration.

Architecture Diagram

User
  |
  v
Code Review Tool
  |
  v
Checklist Engine
  |
  +------------------+------------------+
  |                  |                  |
Syntax Checker   Design Validator   Best Practices Checker
  |                  |                  |
  +------------------+------------------+
            |
            v
       Report Generator
            |
            v
          User

Components

User

actor

Person performing the code review using the tool

Code Review Tool

service

Interface for users to submit code and receive review feedback

Checklist Engine

service

Core logic that applies the LLD code review checklist rules

Syntax Checker

service

Validates code syntax and formatting against standards

Design Validator

service

Checks adherence to low-level design principles and patterns

Best Practices Checker

service

Ensures code follows industry best practices and maintainability guidelines

Report Generator

service

Compiles checklist results into a clear, actionable report for the user

Request Flow - 11 Hops

User → Code Review Tool

Code Review Tool → Checklist Engine

Checklist Engine → Syntax Checker

Checklist Engine → Design Validator

Checklist Engine → Best Practices Checker

Syntax Checker → Checklist Engine

Design Validator → Checklist Engine

Best Practices Checker → Checklist Engine

Checklist Engine → Report Generator

Report Generator → Code Review Tool

Code Review Tool → User

Failure Scenario

Component Fails:Checklist Engine

Impact:Code review process halts; no validation results generated; user cannot get feedback

Mitigation:Implement redundancy with fallback instances; queue requests for retry; notify user of temporary unavailability

Architecture Quiz - 3 Questions

Which component checks if the code follows the correct syntax and formatting?

A Design Validator

B Syntax Checker

C Best Practices Checker

D Report Generator

Design Principle

This architecture separates concerns by dividing the code review process into specialized components, enabling scalability and maintainability. The Checklist Engine orchestrates validation steps, ensuring modular checks for syntax, design, and best practices, while the Report Generator consolidates feedback for clear user communication.

Practice

1. Which of the following is the MOST important focus when reviewing a Low-Level Design (LLD) document?

easy

A. Clarity and correctness of the design

B. The color scheme of the document

C. The number of pages in the document

D. The font style used

Solution

1. Step 1: Understand the purpose of LLD review

   The main goal is to ensure the design is clear and correct so developers can implement it properly.

2. Step 2: Evaluate options based on relevance

   Options A, B, and D relate to formatting, which is less critical than clarity and correctness.

3. Final Answer:

   Clarity and correctness of the design -> Option A

4. Quick Check:

   Focus on clarity and correctness = C [OK]

Hint: Focus on design clarity and correctness first [OK]

Common Mistakes:

• Focusing on document style over content
• Ignoring correctness for aesthetics
• Confusing LLD with high-level design

2. Which checklist item should be included to ensure modularity in an LLD review?

easy

A. Ensure the document has a table of contents

B. Check if the design uses consistent variable names

C. Count the total number of classes

D. Verify if components have clear, single responsibilities

Solution

1. Step 1: Understand modularity in design

   Modularity means breaking the system into parts that each do one thing well.

2. Step 2: Match options to modularity

   Verify if components have clear, single responsibilities directly relates to single responsibility, a key modularity principle. Others are unrelated.

3. Final Answer:

   Verify if components have clear, single responsibilities -> Option D

4. Quick Check:

   Modularity = single responsibility components [OK]

Hint: Look for single responsibility to ensure modularity [OK]

Common Mistakes:

• Confusing naming consistency with modularity
• Counting classes without checking responsibilities
• Focusing on document formatting

3. Given this checklist item: "Ensure all public methods have clear input and output definitions." What is the MOST likely outcome if this is NOT followed?

medium

A. Developers may implement methods incorrectly due to unclear contracts.

B. The system will automatically generate method documentation.

C. The code will run faster.

D. The design will have fewer classes.

Solution

1. Step 1: Understand the role of input/output definitions

   Clear definitions guide developers on how to use methods correctly.

2. Step 2: Analyze consequences of missing definitions

   Without clear contracts, developers may misunderstand method usage, causing errors.

3. Final Answer:

   Developers may implement methods incorrectly due to unclear contracts. -> Option A

4. Quick Check:

   Unclear method contracts = incorrect implementation [OK]

Hint: Clear method contracts prevent implementation errors [OK]

Common Mistakes:

• Assuming code runs faster without definitions
• Thinking documentation is auto-generated
• Confusing method count with clarity

4. You find a design where security considerations are missing in the LLD. What is the BEST immediate action during the code review?

medium

A. Approve the design since security is handled later.

B. Ignore security as it is not part of LLD.

C. Request adding security checks and data validation in the design.

D. Suggest removing modularity to simplify security.

Solution

1. Step 1: Recognize importance of security in LLD

   Security should be considered early to avoid costly fixes later.

2. Step 2: Choose action that improves design quality

   Requesting security checks and validation ensures design is robust and safe.

3. Final Answer:

   Request adding security checks and data validation in the design. -> Option C

4. Quick Check:

   Missing security = request additions [OK]

Hint: Always include security early in design reviews [OK]

Common Mistakes:

• Ignoring security until later stages
• Approving incomplete designs
• Removing modularity harms security

5. During a code review for a complex LLD, you notice the design lacks scalability considerations and testability is weak. Which combined checklist items should you prioritize to improve the design?

hard

A. Increase code comments and skip testing details.

B. Add modular components with clear interfaces and include unit test plans.

C. Focus only on UI design and ignore backend scalability.

D. Reduce the number of classes and remove error handling.

Solution

1. Step 1: Identify key improvements for scalability and testability

   Modular components with clear interfaces help scale and isolate parts for testing.

2. Step 2: Match checklist items to these improvements

   Including unit test plans ensures testability is addressed alongside modularity.

3. Final Answer:

   Add modular components with clear interfaces and include unit test plans. -> Option B

4. Quick Check:

   Modularity + testing plans = better scalability and testability [OK]

Hint: Combine modularity and testing for scalable, testable design [OK]

Common Mistakes:

• Removing error handling weakens design
• Ignoring backend scalability
• Focusing only on comments without tests