Code review checklist for LLD - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if the design follows the {{BLANK_1}} principle.

LLD

if design.adheres_to("[1]"):
    print("Design is modular and easy to maintain.")

Drag options to blanks, or click blank then click option'

ASingle Responsibility

BOpen-Closed

CLiskov Substitution

DDependency Inversion

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing Single Responsibility with Open-Closed principle.

The Single Responsibility Principle ensures each module has one clear responsibility, making the design modular and maintainable.

2fill in blank

medium

Complete the code to validate if the design uses {{BLANK_1}} to reduce tight coupling.

LLD

if design.uses("[1]"):
    print("Design is loosely coupled.")

Drag options to blanks, or click blank then click option'

Ainheritance

Bhardcoded dependencies

Cglobal variables

Dinterfaces

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing inheritance which can increase coupling.

Using interfaces helps reduce tight coupling by allowing modules to interact through abstractions.

3fill in blank

hard

Fix the error in the checklist code to ensure {{BLANK_1}} is properly checked.

LLD

if not design.has_clear_[1]():
    raise ValueError("Design lacks clarity in this aspect.")

Drag options to blanks, or click blank then click option'

Anaming

Bcomments

Cinterfaces

Ddependencies

Attempts:

3 left

💡 Hint

Common Mistakes

Checking interfaces instead of naming clarity.

Clear naming is essential for understanding design elements easily.

4fill in blank

hard

Fill both blanks to verify design {{BLANK_1}} and {{BLANK_2}}.

LLD

if design.has_[1]() and design.is_[2]():
    print("Design is scalable and maintainable.")

Drag options to blanks, or click blank then click option'

Amodularity

Bperformance

Cextensible

Dtestable

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing performance or testable which are important but not the focus here.

Modularity and extensibility are key for scalable and maintainable designs.

5fill in blank

hard

Fill all three blanks to check design {{BLANK_1}}, {{BLANK_2}}, and {{BLANK_3}}.

LLD

if design.is_[1]() and design.has_[2]() and design.supports_[3]():
    print("Design meets quality standards.")

Drag options to blanks, or click blank then click option'

Atestable

Bdocumentation

Cscalability

Dsecurity

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing security with scalability or testability.

Testability, documentation, and scalability are crucial for high-quality designs.

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