Duplications

Let’s look at how to address code duplication in code reviews. We’ll show you a simple example and explain why the feedback matters.

The Scenario

A developer has written code to validate user input in multiple places. The code works but has duplicated validation logic.

function validateEmail(email: string) {
  if (!email || !email.includes('@')) {
    throw new Error('Invalid email')
  }
}
 
function validateUserEmail(user: User) {
  if (!user.email || !user.email.includes('@')) {
    throw new Error('Invalid email')
  }
}

PR Comment

Choose the comment that you think is the most constructive and helpful.

Aurie Chocolatecommented on Apr 2, 2025

Consider reusing the existing validation function.

⚠️

Nit Approach

• The recommendation focuses only on the technical solution
• Doesn’t explain the full benefits of reducing duplication
• Misses the opportunity to discuss maintainability
• Doesn’t acknowledge the working implementation

Karylin Coppercommented on Apr 2, 2025

Great work on the email validation! Reusing the existing validation function helps maintain consistency and makes future updates easier. This follows the DRY (Don’t Repeat Yourself) principle. Here’s how we can improve it:

userValidation.ts

function validateEmail(email: string) {
  if (!email || !email.includes('@')) {
    throw new Error('Invalid email')
  }
}
 
function validateUserEmail(user: User) {
  validateEmail(user.email) // Reuse the validation logic
}