How does this skill help with legacy code?

It provides specific techniques for breaking dependencies and adding safety nets to code that wasn't originally designed for testing, making refactoring much safer.

When should I use characterization tests?

Use characterization tests when you encounter unfamiliar code and need to document its actual current behavior before attempting to refactor or change it.

What is a 'seam' in software testing?

A seam is a location where you can alter code behavior without editing the source file directly, allowing you to substitute production dependencies with test doubles.

What is the difference between sensing and separation?

Sensing is about verifying the effects of your code (what it did), while separation is about isolating code from its dependencies so it can run independently in a test environment.

What are testing patterns in Claude Code?

Testing patterns are specialized capabilities that guide Claude in applying proven software testing strategies, such as the Seam Model and characterization tests, to your codebase.

Testing Patterns & Legacy Code Refactoring

Name: Testing Patterns & Legacy Code Refactoring
Author: primeinc

byprimeinc

Security & Testing

Provides proven strategies and patterns for testing legacy code and breaking complex dependencies safely.

About

This skill equips Claude with advanced testing methodologies inspired by Michael Feathers' 'Working Effectively with Legacy Code.' It addresses the 'Testing Dilemma' by providing specific techniques to add tests to existing, tightly coupled code without breaking functionality. By utilizing concepts like the Seam Model, characterization tests, and dependency breaking patterns, it enables developers to refactor safely, understand unfamiliar codebases, and implement new features using 'Sprout' or 'Wrap' methods. It is an essential companion for developers working on complex systems where traditional unit testing is difficult to apply.

Key Features

Advanced dependency breaking techniques like interface extraction and constructor parameterization
Safe behavioral expansion via Sprout Method, Sprout Class, and Wrap Method
Implementation of characterization tests to document actual code behavior
0 GitHub stars
Identification of object and link seams for behavior alteration
Strategic test placement using 'pinch points' and 'effect sketches'

Use Cases

Refactoring a large legacy codebase that lacks unit tests
Decoupling tightly integrated classes to enable isolated testing
Documenting the behavior of unfamiliar code before making changes

About

Key Features

Advanced dependency breaking techniques like interface extraction and constructor parameterization
Safe behavioral expansion via Sprout Method, Sprout Class, and Wrap Method
Implementation of characterization tests to document actual code behavior
0 GitHub stars
Identification of object and link seams for behavior alteration
Strategic test placement using 'pinch points' and 'effect sketches'

Use Cases

Refactoring a large legacy codebase that lacks unit tests
Decoupling tightly integrated classes to enable isolated testing
Documenting the behavior of unfamiliar code before making changes