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Agustín Rodríguez
Agustín Rodríguez

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Refactor Smart Today, Move Faster Tomorrow — Part 2: Plan Your Refactor Step by Step

So, you've confirmed that your refactor is necessary.
Now it's time to plan it right — because a poorly scoped or unstructured refactor is a trap that can drain weeks of work and leave everything worse than before.

Let's break it down.


🎯 Choose the Right Strategy

There's no single "best" approach to refactoring, but here are common strategies — and when to use them:

1. Incremental Refactor (Recommended for Live Systems)

Refactor bit by bit, keeping the system functional at all times.

✅ Pros: Safe, gradual, easier to test
⚠️ Cons: Requires discipline and clear boundaries
✅ Best for: Actively used systems, critical codebases, or anything in production

2. Branch-based Refactor (When Changes Are Too Invasive)

Fork the code into a separate branch, refactor freely, and merge later.

✅ Pros: Total freedom to redesign
⚠️ Cons: Merge hell, risk of long-living branches, hard to keep in sync
✅ Best for: Isolated modules, internal tools, greenfield components

3. Strangler Fig Pattern (Great for Legacy Systems)

Wrap and slowly replace legacy logic, one endpoint or feature at a time.

✅ Pros: Legacy coexists with new code, safer evolution
⚠️ Cons: Requires architectural support (e.g., routing layers, boundaries)


🗂️ Control the Scope or You'll Never Finish

One of the biggest risks in a refactor is the infinite scope creep.
You touch one piece, which leads to another, and then another... and before you know it, it's a rewrite.

Avoid this by:

  • Defining clear boundaries — "Only refactor the email dispatch logic"
  • Having non-negotiable out-of-scope rules — "Don't rewrite the frontend now"
  • Splitting the work into atomic, testable steps

💡 Tip: Track tasks in a checklist. Treat each step like a mini-feature.


🧱 Pick an Architecture or Pattern (Don't Wing It)

Before you start moving code around, ask yourself:
What kind of structure are we aiming for?
Without a vision, you'll likely make it different, not better.

Examples:

  • Clean or Hexagonal architecture
  • Adapter pattern to swap external services
  • Strategy pattern to simplify logic by behavior
  • Service layer for reusable business logic
  • Ports and adapters to isolate frameworks

🧠 Refactor is not just renaming variables — it's about redesigning how things work internally.


📦 Stabilize Interfaces (Create Contracts)

Even during a refactor, some parts of your system can't change — external APIs, third-party expectations, or other modules still depending on them.

  • Define stable interfaces or DTOs (data transfer objects)
  • Keep method signatures consistent while you migrate under the hood
  • Use adapters to convert legacy format to the new one temporarily

This makes it easier to refactor one part without breaking everything else.


🚩 Use Feature Flags

If your refactor affects a feature that's already live, wrap the new version in a flag so you can:

  • Test it in staging
  • Gradually roll it out
  • Roll back instantly if needed

This adds safety — especially when combined with CI/CD pipelines.


🧪 Define a Refactor Testing Strategy

You need different levels of tests to support your refactor:

  • Unit tests for small modules
  • Integration tests for connections between modules
  • Regression tests to make sure nothing breaks
  • (Optional) Snapshots or visual diffs for UIs

🔍 Also, use coverage tools to find untested danger zones before you touch them.


🛠️ Checklist Before the First Commit

Before writing any code:

  • [ ] Refactor strategy selected (Incremental, Branch, Strangler)
  • [ ] Scope clearly defined and limited
  • [ ] Architectural target or pattern chosen
  • [ ] Interfaces/contracts stabilized
  • [ ] Feature flags planned (if needed)
  • [ ] Tests prepared or planned
  • [ ] Metrics defined (to validate results later)

Cover image credit: Chris Ried, via Unsplash

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