Can this skill detect incomplete mocks?

Yes, it encourages mirroring the complete real-world API structure in your mocks to prevent silent failures where downstream code expects fields that were omitted from a partial mock.

Why is testing mock behavior discouraged?

Asserting that a mock exists or was called often tells you nothing about the actual application behavior. This skill ensures you test what the code does, not just that a mock was triggered.

Does this skill work with existing test frameworks?

Yes, it provides conceptual guidance and gate functions applicable to Vitest, Jest, React Testing Library, and other modern TypeScript/JavaScript testing ecosystems.

What are the core principles of the Testing Anti-Patterns skill?

The skill follows three 'Iron Laws': never test mock behavior, never add test-only methods to production classes, and never mock without fully understanding the underlying dependencies.

How does this skill help with production code cleanliness?

It uses a gate function to intercept the addition of methods intended only for testing. If a method isn't used in production, the skill directs you to move it to a dedicated test utility file instead.

Testing Anti-Patterns Guard

Name: Testing Anti-Patterns Guard
Author: Kingly-Agency

byKingly-Agency

セキュリティとテスト

Prevents common software testing mistakes by enforcing best practices for mocking, production code isolation, and Test-Driven Development (TDD).

概要

This skill acts as an automated mentor for Claude Code, ensuring that test suites remain robust and maintainable. It enforces 'Iron Laws' that prevent developers from testing mock behavior rather than real logic, polluting production code with test-only methods, and creating incomplete mocks that lead to silent failures. By integrating gate functions into the development workflow, it encourages a strict TDD approach that identifies architectural flaws early and ensures tests provide real value rather than false confidence.

主な機能

Blocks test-only methods from entering production classes to maintain separation of concerns
0 GitHub stars
Prevents assertions on mock elements to ensure real component behavior is verified
Promotes strict TDD cycles to ensure implementation follows test requirements
Validates mock completeness against real API structures to avoid downstream errors
Enforces dependency analysis before mocking to prevent broken test logic

ユースケース

Refactoring brittle test suites that fail due to implementation details rather than logic errors
Guiding junior developers in writing meaningful tests that avoid common mocking pitfalls
Enforcing clean code standards during the transition from unit to integration testing

概要

主な機能

Blocks test-only methods from entering production classes to maintain separation of concerns
0 GitHub stars
Prevents assertions on mock elements to ensure real component behavior is verified
Promotes strict TDD cycles to ensure implementation follows test requirements
Validates mock completeness against real API structures to avoid downstream errors
Enforces dependency analysis before mocking to prevent broken test logic

ユースケース

Refactoring brittle test suites that fail due to implementation details rather than logic errors
Guiding junior developers in writing meaningful tests that avoid common mocking pitfalls
Enforcing clean code standards during the transition from unit to integration testing