refactor-test_skill

Overview

This skill verifies test coverage and readiness before refactoring to reduce regression risk. It maps current tests, identifies coverage gaps, and produces prioritized recommendations and verification checkpoints. The goal is to make refactoring safe, measurable, and incremental.

How this skill works

The skill inspects test suites and source files in the refactoring scope, classifies tests as unit, integration, or brittle implementation-dependent tests, and highlights untested code paths. It outputs a gap analysis with impact ratings, recommends characterization and golden-master tests, and defines stepwise verification gates and post-deployment checks.

When to use it

• Before starting any non-trivial refactor of existing code
• When migrating modules, APIs, or shared libraries
• Prior to changing business logic, error handling, or async/concurrent code
• To validate readiness for large-scale cleanup or performance optimizations
• When preparing a safe rollout with incremental verification checkpoints

Best practices

• Map coverage per file and per behavior, not just overall percentage
• Prioritize tests for critical paths and public APIs first
• Add characterization or golden-master tests for complex or poorly understood behavior
• Convert brittle tests to behavior-driven assertions that avoid implementation details
• Define test gates and smoke tests for each migration step and include performance checks

Example use cases

• Verify tests cover authentication, authorization, and payment flows before refactoring core services
• Identify missing integration tests between frontend rendering and backend APIs before UI refactor
• Create golden-master tests to lock complex serialization formats before changing serializers
• Plan test gates and smoke tests when splitting a monolith into services
• Add contract tests for public APIs before modifying endpoints or payload shapes