Unit Testing

Build backend AI with Vercel AI SDK v5/v6. v6 stable introduces Output API (Output.object/array/choice replace deprecated generateObject/streamObject), plus speech synthesis, transcription, image generation, embeddings, reranking, MCP tools, and middleware. Covers v4→v5 migration, latest models (GPT-5.2, Claude 4.x, Gemini 2.5), Workers startup fix, and 12 error solutions. Use when: implementing AI SDK v5/v6, using Output API, speech/transcription/image features, embeddings, MCP tools, migrating v4→v5, troubleshooting errors, or fixing Workers startup issues.

This skill should be used when working with xterm.js terminal implementations, React-based terminal applications, WebSocket terminal communication, or refactoring terminal-related code. It provides battle-tested patterns, common pitfalls, and debugging strategies learned from building production terminal applications.

Complete browser automation with Playwright. Auto-detects dev servers, writes clean test scripts to /tmp. Test pages, fill forms, take screenshots, check responsive design, validate UX, test login flows, check links, automate any browser task. Use when user wants to test websites, automate browser interactions, validate web functionality, or perform any browser-based testing.

Consumer-driven contract testing for microservices using Pact, schema validation, API versioning, and backward compatibility testing. Use when testing API contracts or coordinating distributed teams.

Apply context-driven testing principles where practices are chosen based on project context, not universal 'best practices'. Use when making testing decisions, questioning dogma, or adapting approaches to specific project needs.

Advanced test reporting, quality dashboards, predictive analytics, trend analysis, and executive reporting for QE metrics. Use when communicating quality status, tracking trends, or making data-driven decisions.

Strategic regression testing with test selection, impact analysis, and continuous regression management. Use when verifying fixes don't break existing functionality, planning regression suites, or optimizing test execution for faster feedback.

WCAG 2.2 compliance testing, screen reader validation, and inclusive design verification. Use when ensuring legal compliance (ADA, Section 508), testing for disabilities, or building accessible applications for 1 billion disabled users globally.

Test quality validation through mutation testing, assessing test suite effectiveness by introducing code mutations and measuring kill rate. Use when evaluating test quality, identifying weak tests, or proving tests actually catch bugs.

Regulatory compliance testing for GDPR, CCPA, HIPAA, SOC2, PCI-DSS and industry-specific regulations. Use when ensuring legal compliance, preparing for audits, or handling sensitive data.

Orchestrate quality engineering across CI/CD pipeline phases. Use when designing test strategies, planning quality gates, or implementing shift-left/shift-right testing.

n8n expression syntax validation, context-aware testing, common pitfalls detection, and performance optimization. Use when validating n8n expressions and data transformations.

Move testing activities earlier in the development lifecycle to catch defects when they're cheapest to fix. Use when implementing TDD, CI/CD, or early quality practices.

Test environment provisioning, infrastructure as code for testing, Docker/Kubernetes for test environments, service virtualization, and cost optimization. Use when managing test infrastructure, ensuring environment parity, or optimizing testing costs.

Credential exposure detection, OAuth flow validation, API key management testing, and data sanitization verification for n8n workflows. Use when validating n8n workflow security.

Unvarnished technical criticism combining Linus Torvalds' precision, Gordon Ramsay's standards, and James Bach's BS-detection. Use when code/tests need harsh reality checks, certification schemes smell fishy, or technical decisions lack rigor. No sugar-coating, just surgical truth about what's broken and why.

Webhook testing, schedule validation, event-driven triggers, and polling mechanism testing for n8n workflows. Use when testing how workflows are triggered.

Database schema validation, data integrity testing, migration testing, transaction isolation, and query performance. Use when testing data persistence, ensuring referential integrity, or validating database migrations.

Comprehensive mobile testing for iOS and Android platforms including gestures, sensors, permissions, device fragmentation, and performance. Use when testing native apps, hybrid apps, or mobile web, ensuring quality across 1000+ device variants.

Comprehensive n8n workflow testing including execution lifecycle, node connection patterns, data flow validation, and error handling strategies. Use when testing n8n workflow automation applications.