Amey-Thakur Refactoring
A refactor changes structure while behavior stays identical. The moment behavior changes on purpose, it is a feature; by accident, a bug. Keep the line sharp.
Method
- Secure the net first. Confirm the tests around the target pass and actually pin its behavior. If coverage is thin, write characterization tests before touching anything: capture what the code does now, even its oddities. An odd behavior may be load-bearing.
- Name the smell and the target shape. "Three near-copies of this query builder → one function with two parameters." If you cannot state the after-state in a sentence, you are wandering, not refactoring.
- Move in reversible steps, green after each. Rename; extract function; inline; move; then delete the old path. Each step compiles, passes, and could ship. Twenty two-minute steps beat one two-hour rewrite in every dimension that matters: reviewability, bisectability, abort-ability.
- Separate refactor commits from behavior commits. A reviewer must be able to skim a refactor commit ("no behavior change") and scrutinize the small behavior commit. Mixed commits get neither reading.
- Follow the house style, even where you prefer another. A codebase with one accent is maintainable; your improvement in a foreign accent is someone else's cleanup ticket.
- Stop at the target. The neighboring mess you noticed goes on a list, not into this change. Scope creep is how refactors become rewrites and rewrites become incidents.
Judgment calls
- Duplication: two copies are cheaper than the wrong abstraction; three copies with the same change-reason justify extraction. Extract for shared meaning, not shared characters.
- Small functions: extraction pays when the name says something the code cannot; a five-line function called once with a vague name is indirection, not clarity.
- Dead code: delete it, do not comment it out. Version control is the attic.
Litmus tests
- Could every commit in the series ship alone?
- Did any test's assertions change? (Renames aside: that is the tell that behavior moved.)
- Is the diff smaller than the improvement it buys?