Unit Testing

Complete guide to Next.js 16 features, breaking changes, and migration from v15. Use when building new Next.js projects or upgrading existing ones to leverage Turbopack, Cache Components, and latest performance optimizations.

Write TypeScript runtime and type tests (project)

Creates and analyzes tests using Vitest and MSW patterns. Generates test builders, mocks repositories, and configures integration tests. Triggers on: write tests, test coverage, Vitest, MSW mock, vi.fn, vi.mock, unit test, integration test, test builder, mock setup, test failure.

test-engineer skill Trigger terms: testing, unit tests, integration tests, E2E tests, test cases, test coverage, test automation, test plan, test design, TDD, test-first Use when: User requests involve test engineer tasks.

Implement Clean Architecture principles in TypeScript for maintainable, testable, and framework-independent applications. Use when designing new TypeScript applications, refactoring existing code, or implementing domain-centric Node.js applications.

Internal skill. Use cc10x-router for all development tasks.

Build modern mobile applications with React Native, Flutter, Swift/SwiftUI, and Kotlin/Jetpack Compose. Covers mobile-first design principles, performance optimization (battery, memory, network), offline-first architecture, platform-specific guidelines (iOS HIG, Material Design), testing strategies, security best practices, accessibility, app store deployment, and mobile development mindset. Use when building mobile apps, implementing mobile UX patterns, optimizing for mobile constraints, or making native vs cross-platform decisions.

Copilot agent that assists with comprehensive QA strategy and test planning to ensure product quality through systematic testing and quality metrics Trigger terms: QA, quality assurance, test strategy, QA plan, quality metrics, test planning, quality gates, acceptance testing, regression testing Use when: User requests involve quality assurance tasks.

Copilot agent that assists with comprehensive QA strategy and test planning to ensure product quality through systematic testing and quality metrics Trigger terms: QA, quality assurance, test strategy, QA plan, quality metrics, test planning, quality gates, acceptance testing, regression testing Use when: User requests involve quality assurance tasks.

Copilot agent that assists with user interface and experience design, wireframes, prototypes, design systems, and usability testing Trigger terms: UI design, UX design, wireframe, mockup, prototype, user interface, user experience, design system, component library, accessibility, responsive design Use when: User requests involve ui ux designer tasks.

test-engineer skill Trigger terms: testing, unit tests, integration tests, E2E tests, test cases, test coverage, test automation, test plan, test design, TDD, test-first Use when: User requests involve test engineer tasks.

Validates complete requirements traceability across EARS requirements → design → tasks → code → tests. Trigger terms: traceability, requirements coverage, coverage matrix, traceability matrix, requirement mapping, test coverage, EARS coverage, requirements tracking, traceability audit, gap detection, orphaned requirements, untested code, coverage validation, traceability analysis. Enforces Constitutional Article V (Traceability Mandate) with comprehensive validation: - Requirement → Design mapping (100% coverage) - Design → Task mapping - Task → Code implementation mapping - Code → Test mapping (100% coverage) - Gap detection (orphaned requirements, untested code) - Coverage percentage reporting - Traceability matrix generation Use when: user needs traceability validation, coverage analysis, gap detection, or requirements tracking across the full development lifecycle.

Implement Clean Architecture principles in Python to create maintainable, testable, and framework-independent applications. Use when designing new Python applications, refactoring existing code, or implementing domain-driven designs.

Internal skill. Use cc10x-router for all development tasks.

Implement Clean Architecture principles in Go to create maintainable, testable, and framework-independent applications. Use when designing new Go applications or refactoring existing Go codebases.

Validates compliance with 9 Constitutional Articles and Phase -1 Gates before implementation. Trigger terms: constitution, governance, compliance, validation, constitutional compliance, Phase -1 Gates, simplicity gate, anti-abstraction gate, test-first, library-first, EARS compliance, governance validation, constitutional audit, compliance check, gate validation. Enforces all 9 Constitutional Articles with automated validation: - Article I: Library-First Principle - Article II: CLI Interface Mandate - Article III: Test-First Imperative - Article IV: EARS Requirements Format - Article V: Traceability Mandate - Article VI: Project Memory - Article VII: Simplicity Gate - Article VIII: Anti-Abstraction Gate - Article IX: Integration-First Testing Runs Phase -1 Gates before any implementation begins. Use when: validating project governance, checking constitutional compliance, or enforcing quality gates before implementation.

Systematic debugging framework ensuring root cause investigation before fixes. Includes four-phase debugging process, backward call stack tracing, multi-layer validation, and verification protocols. Use when encountering bugs, test failures, unexpected behavior, performance issues, or before claiming work complete. Prevents random fixes, masks over symptoms, and false completion claims.

Validates compliance with 9 Constitutional Articles and Phase -1 Gates before implementation. Trigger terms: constitution, governance, compliance, validation, constitutional compliance, Phase -1 Gates, simplicity gate, anti-abstraction gate, test-first, library-first, EARS compliance, governance validation, constitutional audit, compliance check, gate validation. Enforces all 9 Constitutional Articles with automated validation: - Article I: Library-First Principle - Article II: CLI Interface Mandate - Article III: Test-First Imperative - Article IV: EARS Requirements Format - Article V: Traceability Mandate - Article VI: Project Memory - Article VII: Simplicity Gate - Article VIII: Anti-Abstraction Gate - Article IX: Integration-First Testing Runs Phase -1 Gates before any implementation begins. Use when: validating project governance, checking constitutional compliance, or enforcing quality gates before implementation.

Copilot agent that assists with user interface and experience design, wireframes, prototypes, design systems, and usability testing Trigger terms: UI design, UX design, wireframe, mockup, prototype, user interface, user experience, design system, component library, accessibility, responsive design Use when: User requests involve ui ux designer tasks.

Activate when users ask about Claude Code installation, slash commands (/cook, /plan, /fix, /test, /docs, /design, /git), creating/managing Agent Skills, configuring MCP servers, setting up hooks/plugins, IDE integration (VS Code, JetBrains), CI/CD workflows, enterprise deployment (SSO, RBAC, sandboxing), troubleshooting authentication/performance issues, or advanced features (extended thinking, caching, checkpointing).