skills/curated/vitest/SKILL.md
Vitest fast unit testing framework powered by Vite with Jest-compatible API. Use when writing tests, mocking, configuring coverage, or working with test filtering and fixtures.
npx skillsauth add pedronauck/skills vitestInstall this skill globally with one command. Works with Claude Code, Cursor, and Windsurf.
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Vitest is a next-generation testing framework powered by Vite. It provides a Jest-compatible API with native ESM, TypeScript, and JSX support out of the box. Vitest shares the same config, transformers, resolvers, and plugins with your Vite app.
Key Features:
The skill is based on Vitest 3.x, generated at 2026-01-28.
| Topic | Description | Reference | |-------|-------------|-----------| | Configuration | Vitest and Vite config integration, defineConfig usage | core-config | | CLI | Command line interface, commands and options | core-cli | | Test API | test/it function, modifiers like skip, only, concurrent | core-test-api | | Describe API | describe/suite for grouping tests and nested suites | core-describe | | Expect API | Assertions with toBe, toEqual, matchers and asymmetric matchers | core-expect | | Hooks | beforeEach, afterEach, beforeAll, afterAll, aroundEach | core-hooks |
| Topic | Description | Reference | |-------|-------------|-----------| | Mocking | Mock functions, modules, timers, dates with vi utilities | features-mocking | | Snapshots | Snapshot testing with toMatchSnapshot and inline snapshots | features-snapshots | | Coverage | Code coverage with V8 or Istanbul providers | features-coverage | | Test Context | Test fixtures, context.expect, test.extend for custom fixtures | features-context | | Concurrency | Concurrent tests, parallel execution, sharding | features-concurrency | | Filtering | Filter tests by name, file patterns, tags | features-filtering |
| Topic | Description | Reference | |-------|-------------|-----------| | Vi Utilities | vi helper: mock, spyOn, fake timers, hoisted, waitFor | advanced-vi | | Environments | Test environments: node, jsdom, happy-dom, custom | advanced-environments | | Type Testing | Type-level testing with expectTypeOf and assertType | advanced-type-testing | | Projects | Multi-project workspaces, different configs per project | advanced-projects |
development
Deep review of branch diffs, working trees, or GitHub PRs at any size. Use when the user asks for CodeRabbit-grade review, an incremental re-review after new pushes, publication of findings to a PR, a cross-LLM peer-review verdict round, or conformance review against spec artifacts. Don't use for applying fixes, reviewing specs or PRDs as documents, or quick single-file feedback.
tools
Orchestrate Claude and Codex worker TUIs from a controller agent through herdr panes and the herdr socket CLI. Use when delegating bounded tasks to herdr worker panes, running user-activated plan-first delegations (Claude Code plan mode, Codex Plan mode), waiting on native agent status (idle, working, blocked, done), or verifying worker reports. Workers launch as interactive TUIs via herdr agent start — never through headless runners (compozy exec, claude -p, codex exec). Not for cmux workspaces (see cmux-orchestration) and not for end-user herdr control.
tools
TanStack Query, Router, and Form patterns for React. Use when writing useQuery/queryOptions, mutations, caching, file-based routes, search params, loaders, or TanStack Form validation. Don't use for TanStack Start, TanStack DB/collections, Zustand client state, or non-TanStack routing.
development
Use when the user wants to design, redesign, shape, critique, audit, polish, clarify, distill, harden, optimize, adapt, animate, colorize, extract, or otherwise improve a frontend interface. Covers websites, landing pages, dashboards, product UI, app shells, components, forms, settings, onboarding, and empty states. Handles UX review, visual hierarchy, information architecture, cognitive load, accessibility, performance, responsive behavior, theming, anti-patterns, typography, fonts, spacing, layout, alignment, color, motion, micro-interactions, UX copy, error states, edge cases, i18n, and reusable design systems or tokens. Also use for bland designs that need to become bolder or more delightful, loud designs that should become quieter, live browser iteration on UI elements, or ambitious visual effects that should feel technically extraordinary. Not for backend-only or non-UI tasks.