How does this skill improve my TDD workflow?

It enforces the 'Red-Green-Refactor' cycle by providing gate functions that help you verify if a test is checking real logic before you start mocking dependencies.

Why is it bad to add test-only methods to production code?

Adding test-only methods violates the YAGNI principle and separation of concerns, making the production API confusing and potentially introducing bugs or security risks.

How does the skill handle incomplete mocks?

It enforces an 'Iron Rule' where mocks must mirror the complete data structure of the real API, preventing silent failures that occur when downstream code tries to access omitted fields.

What are testing anti-patterns?

Testing anti-patterns are common but counterproductive habits, such as asserting that a mock was called rather than checking the side effect, or polluting production classes with methods used only for testing.

Testing Anti-Patterns Guard

Name: Testing Anti-Patterns Guard
Author: yusoofsh

byyusoofsh

0•

Security & Testing

Prevents common software testing mistakes by enforcing strict TDD principles and identifying fragile mock implementations.

This Claude Code Skill acts as a guardian for your testing suite, ensuring that tests verify real application behavior rather than the implementation details of mocks. It provides actionable guidance to prevent 'production pollution'—the practice of adding test-only methods to production classes—and helps developers avoid incomplete mocks that lead to silent failures. By integrating strict gate functions and TDD patterns, it helps teams maintain clean, reliable, and decoupled test suites that actually validate the system's logic rather than its test doubles.

Key Features

01Identifies and blocks assertions that test mock existence instead of behavior

02Promotes strict TDD cycles to ensure tests are meaningful and properly isolated

03Ensures structural completeness in mock data structures to prevent downstream failures

040 GitHub stars

05Detects and discourages the addition of test-only methods to production codebases

06Provides interactive Gate Functions to validate mocking decisions before implementation

Use Cases

01Designing robust integration tests that accurately mirror real API response structures

02Reviewing existing test suites to identify fragile assertions and over-mocking

03Refactoring production classes to move test-specific logic into external utilities

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add yusoofsh/dotfiles testing-anti-patterns

For use in Claude.ai and ChatGPT

Download Skill