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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