3 535 testing skills from 425 authors. They run test suites, check accessibility and catch what broke. Half of them fit into 1 800 tokens or less — that is what one costs your context window when the agent loads it. 404 ship runnable scripts rather than instructions alone. 2 of them cannot work without an MCP server, most often rube. We also found 403 copies of these same skills sitting in other people's repositories — counted once here, not 403 times.
3 535 unique 425 authors 2 156 updated this month 319 from vendors
Use for nontrivial Effect-TS work including services/layers, typed errors, Schema/JSONSchema, Config, runtime/concurrency, @effect/vitest, @effect/ai, @effect/sql, or @prb/effect-next.
mocks, testing utilities, and coverage."
Writes, refactors, and evaluates prompts for LLMs — generating optimized prompt templates, structured output schemas, evaluation rubrics, and test suites. Use when designing prompts for new LLM applications, refactoring existing prompts for better accuracy or token efficiency, implementing chain-of-thought or few-shot learning, creating system prompts with personas and guardrails, building JSON/function-calling schemas, or developing prompt evaluation frameworks to measure and improve model performance.
Assess Azure resource capacity, quota utilization, and growth trends to prevent outages from resource exhaustion. Use when asked about capacity, quotas, scaling readiness, load testing prep, Black Friday readiness, or growth projections.
Testing Craft CMS 5 plugins and modules with Pest — test isolation, database safety, and the markhuot/craft-pest-core harness. ALWAYS load when writing, running, fixing, or reviewing tests for a Craft plugin or module, and whenever a suite touches a real Craft install. Covers why rollback is opt-in, tests/Pest.php + tests/bootstrap.php wiring, phpunit.xml.dist <env> pins (force the DB name and table prefix, default the connection coordinates so CI still connects), why --configuration= defeats DB isolation, installing the plugin under test, pinning the process timezone after app creation, per-test site fixtures, idempotent Install migrations, stale service caches when components get swapped, muting audit sinks, queue stubs, factories, HTTP/DB assertions, CI test jobs. Triggers on: Pest, pestphp, craft-pest-core, markhuot, RefreshesDatabase, InstallsCraft, tests/Pest.php, phpunit.xml.dist, vendor/bin/pest, composer test, ddev craft pest, db_test, CRAFT_DB_DATABASE, CRAFT_DB_TABLE_PREFIX, Entry::factory(), assertDatabaseHas, afterEach, transaction rollback, test site fixture, fixture cleanup sweep, createIndexIfMissing, Db::findForeignKey, UserPermissions::reset(), 'too many keys', 'tests pollute the database', 'tests created thousands of entries', 'passes on dev but fails in isolation', 'passes alone but fails in the suite', 'datetimes off by hours in tests', 'connects locally but not on CI', flaky order-dependent test, no Pest job in CI. Do NOT trigger for front-end/JS testing or PHP style analysis.
Craft CMS 5 plugin and module development — extending Craft with PHP. Covers elements, element queries, services, models, records, controllers, migrations, queue jobs, console commands, field types, native fields, events, behaviors, Twig extensions, widgets, filesystems, permissions, project config, GraphQL, testing, and debugging. Triggers on: beforePrepare()/afterSave()/defineSources()/defineTableAttributes()/attributeHtml(), MemoizableArray, BaseNativeField, EVENT_REGISTER_*/DEFINE_*/BEFORE_*/AFTER_*, CraftVariable, custom element or field type (normalizeValue/serializeValue/inputHtml), webhook, API endpoint, queue/batch job, CP section, dashboard widget, utility page, element action/exporter/condition, registerUserPermissions, requirePermission vs requireAdmin, kebab-case permission handles, allowAdminChanges, canView/canSave/canDelete, defineRules, elevated session, project-config/apply, drafts/revisions, element edit sidebar (EVENT_DEFINE_SIDEBAR_HTML) + toolbar buttons, metaFieldsHtml, VueAdminTable, GeneralConfig, getIsMultiSite/refreshSites stale after creating a site, deleteSite phantom sites, element query stops filtering by siteId, naive UTC datetime columns and strtotime drift, element-query ['like'] tuple matches nothing. Always use when writing, editing, or reviewing Craft plugin/module PHP — even when no API is named. For plugin-specific work also load craft-plugins. Do NOT trigger for front-end Twig (craft-site) or content modeling (craft-content-modeling).
Route OpenSkills development tasks to the right project skill or subagent, including sequencing rules for debugging, feature work, regression checks, and release readiness.
Run deterministic OpenSkills end-to-end validation across runtime tests and example agents, then report tool calls, activation behavior, and regressions.
Prepare and validate OpenSkills release readiness across runtime, bindings, examples, and regression gates with a deterministic checklist and go/no-go outcome.
Producing automated feature demo videos via Playwright E2E tests. Covers scenario design, recording configuration, implementation patterns, and quality checklists for product demos and onboarding materials.
Implementing pure-native app features for iOS (Swift 6.3 + SwiftUI + Liquid Glass), Android (Kotlin 2.4+ + Jetpack Compose + Material 3 Expressive), and macOS desktop (SwiftUI for Mac + AppKit interop, scenes/menu bar/document apps, sandbox + notarization + Sparkle, Mac HIG). Builds production features with @Observable/Swift Concurrency, Compose Strong Skipping, SwiftData/Room, Passkeys, Privacy Manifest, App Intents, Foundation Models/Gemini Nano, and store-compliance staged rollout. Also runs the agent visual loop for screen implementation and visual debugging against a reference design (Xcode MCP RenderPreview, XcodeBuildMCP, mobile-mcp, screenshot diffing). Use when building production iOS/Android/macOS features or iterating a native screen until it matches a design. Not for cross-platform (RN/Flutter/KMP/CMP), porting design (Port), prototypes (Forge), mockup-to-code (Pixel), automating existing Mac apps via AppleScript/JXA (Hearth), test suites (Snap/Voyager), or web (Artisan).
Defining KPIs, designing tracking events, and specifying dashboards. Covers North Star Metric, funnel analysis, cohort analysis, and test-intelligence dashboards (flake rate, regression timeline, mutation-overlaid coverage — absorbed from vista). GA4/Amplitude/Mixpanel/PostHog integration. Use when metrics or test-telemetry dashboards are needed.
Adding edge-case tests, repairing flaky tests, and improving coverage. Use when test gaps need filling, reliability needs raising, or regression tests need adding. Multi-language support (JS/TS, Python, Go, Rust, Java).
Automating iOS UI via XCUITest, accessibility-identifier-driven queries, programmatic screenshot capture, and fastlane snapshot pipelines for App Store assets. Authors XCUITest targets with XCUIApplication/XCUIElement/XCUIElementQuery patterns, Page Objects in Swift, status-bar-clean sessions, and xcodebuild+xcresulttool CI. Use when authoring iOS UI tests or store-screenshot pipelines. Not for cross-platform E2E (Voyager — Appium/Detox/Maestro), iOS feature impl (Native), demo recording (Director), or unit tests (Radar).
Verifying system resilience via load testing, contract testing, chaos engineering, and mutation testing. Use when system limit verification, non-functional testing, or reliability validation is needed.
Investigating git history, analyzing regression root causes, and performing code archaeology. Time-travels through commit history to uncover truth. Use when git history investigation or regression analysis is needed.
Automating browsers via Playwright and Chrome DevTools for data collection, form interaction, screenshot capture, and network monitoring. Task completion focus (vs Voyager for E2E testing).
Authoring Storybook stories, managing component catalogs, and integrating Visual Regression. Covers UI component docs, visual testing, CSF 3.0/Factories. Supports Storybook 10 (ESM-only) and React Cosmos. Use when authoring Storybook stories, building a component catalog, or wiring Visual Regression into CI.
Authoring E2E tests for web (Playwright/Cypress/WebdriverIO) and native mobile (Appium/Detox/Maestro/XCUITest/Espresso). Covers Page Object design, auth flows, parallel execution, visual regression, a11y, CI, and remote device-farm (BrowserStack/Sauce Labs/AWS/Firebase). Use when authoring E2E suites. Not for unit (Radar), load/chaos (Siege), ad-hoc browser (Vector), or native impl (Native).
Systematic root cause analysis for production and development bugs. Hypothesis-driven debugging — never guess-and-check.
Test real system boundaries, not mocks of mocks. Integration tests verify that components work together, not that they work in isolation.
Red-green-refactor cycle with meaningful coverage. Tests are written before implementation. Coverage is a side effect of good tests, not the goal.
Use when the user wants to create a new CLAUDE.md from scratch for a repository, bootstrap project memory for a new repo, set up a repo for Claude Code for the first time, or completely rewrite an existing CLAUDE.md deemed unsalvageable. Produces a lean, high-signal file under 80 lines (120 hard cap) by scanning the repo for mechanical content (stack, commands, structure) and interviewing the user for judgment content (WHY, gotchas, out-of-scope, approval gates, testing philosophy, external docs like Confluence pages). NOT for auditing or incrementally improving an existing CLAUDE.md — that is the claude-md-improver skill's role.
Ecto patterns for Phoenix/Elixir apps. Covers schemas, changesets, migrations, queries, Ecto.Multi, transactions, constraints, associations, pagination, tenant partitioning, performance, and testing.
Production gRPC in Go: protobuf layout, codegen, interceptors, deadlines, error codes, streaming, health checks, TLS, and testing with bufconn
Comprehensive Go testing strategies including table-driven tests, testify assertions, gomock interface mocking, benchmark testing, and CI/CD integration
Production-ready Express.js development covering middleware architecture, error handling, security hardening, testing strategies, and deployment patterns
Hono testing patterns - app.request(), test client, mocking environment, and integration testing strategies
Cypress end-to-end and component testing patterns for web apps: reliable selectors, stable waits, network stubbing, auth handling, CI parallelization, and flake reduction
WordPress plugin and theme testing with PHPUnit integration tests, WP_Mock unit tests, PHPCS coding standards, and CI/CD workflows
pytest - Python's most powerful testing framework with fixtures, parametrization, plugins, and framework integration for FastAPI, Django, Flask
Axum (Rust) web framework patterns for production APIs: routers/extractors, state, middleware, error handling, tracing, graceful shutdown, and testing
Production Fastify (TypeScript) patterns: schema validation, plugins, typed routes, error handling, security hardening, logging, testing with inject, and graceful shutdown
Jest with TypeScript - Industry standard testing framework with 70% market share, mature ecosystem, React Testing Library integration
Vitest - Modern TypeScript testing framework with Vite-native performance, ESM support, and TypeScript-first design
Homebrew formula maintenance workflows for Python CLIs and taps, including version bumps, SHA/resource updates, testing, audits, and releases.
Step-by-step debugging workflow: reproduce the bug, isolate the failing component, trace to root cause, apply a targeted fix, and verify the fix resolves the issue without regressions. Use when you encounter a bug, error, exception, crash, or unexpected behavior that needs troubleshooting.
MCP (Model Context Protocol) server build and evaluation guide, including local conventions for tool surfaces, config, and testing
Comprehensive TDD patterns and practices for all programming languages, eliminating redundant testing guidance per agent.
Test quality inspection framework for reviewing test coverage, identifying gaps, and ensuring comprehensive validation
Never test mock behavior. Never add test-only methods to production classes. Understand dependencies before mocking. Language-agnostic principles with TypeScript/Jest and Python/pytest examples.
Comprehensive web application testing patterns with Playwright selectors, wait strategies, and best practices
> Go error handling patterns, wrapping, sentinel errors, custom error types, and the errors package. Grounded in Effective Go, Go Code Review Comments, and production-proven idioms. Use when implementing error handling, designing error types, debugging error chains, or reviewing error handling patterns. "sentinel errors", "errors.Is", "errors.As". Do NOT use for panic/recover patterns in middleware (use go-api-design) or test assertion errors (use go-test-quality).
> goroutine leaks, memory leaks, OOM kills, race reports, and debugging with delve and pprof. leak", "goroutine count growing", "OOM", "program hangs", "race detector output", "use delve". writing new concurrent code (use go-concurrency-review), or failing test design (use go-test-quality).
> struct design, subtest naming, advanced patterns like test matrices and shared setup, and refactoring bloated tables into clean ones. Use when writing table-driven tests, refactoring test tables, reviewing table test structure, or deciding whether table-driven is the right approach. "test matrix", "parametrize tests", "data-driven test", "refactor test table". Do NOT use for general test strategy, mocking, golden files, or fuzz testing (use go-test-quality). Do NOT use for benchmarks (use go-performance-review).
> golden files, httptest, testcontainers, property-based testing, and fuzz testing. Covers mocking strategies, test isolation, coverage analysis, and test design philosophy. Use when writing tests, improving coverage, reviewing test quality, setting up test infrastructure, or choosing a testing approach. "test helpers", "mock this dependency", "integration test", "fuzz test". Do NOT use for performance benchmarking methodology (use go-performance-review), security testing (use go-security-audit), or table-driven test patterns specifically (use go-test-table-driven).
> golangci-lint setup, test/coverage gates, vulnerability scanning, build matrices, and Makefile targets. "CI is slow", "coverage gate", "build matrix", "write a Makefile", "run govulncheck in CI". auditing dependencies (use go-dependency-audit), or writing the tests themselves (use go-test-quality).
> Enforce testing best practices when writing, reviewing, or improving tests. Covers TDD/red-green-refactor, property-based testing, real objects over mocks, correctness by construction, assertion quality, E2E/contract tests, flaky-test upgrades, mock-reality drift, mutation-style gap analysis, and sabotaged/skipped/weak tests. Use when writing tests, reviewing test quality, fixing flaky tests, improving coverage quality, or when the user mentions TDD, testing, coverage, mocks, invariants, types vs tests, defense in depth, or test quality.