vitest

by antfu

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 skills add https://github.com/antfu/skills --skill vitest Download ZIPGitHub5.5k 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:

• Vite-native: Uses Vite's transformation pipeline for fast HMR-like test updates

• Jest-compatible: Drop-in replacement for most Jest test suites

• Smart watch mode: Only reruns affected tests based on module graph

• Native ESM, TypeScript, JSX support without configuration

• Multi-threaded workers for parallel test execution

• Built-in coverage via V8 or Istanbul

• Snapshot testing, mocking, and spy utilities

The skill is based on Vitest 5.x (beta), generated at 2026-06-22.

Core

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

Features

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 Test Tags Label tests with tags to filter runs and apply shared options features-test-tags Reporters Built-in reporters, default selection, CI/output config features-reporters Benchmarking Write benchmarks with the bench fixture (Tinybench) features-benchmarking

Advanced

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

Related Skills

azure-hosted-copilot-sdk Azure

Build and deploy GitHub Copilot SDK apps to Azure.

vendor-management anthropic

Evaluate, compare, and manage vendor relationships. Trigger with "evaluate this vendor", "compare vendors", "vendor review", "should we renew", "RFP", or when… official

working-with-dbt-mesh dbt-labs

Implements dbt Mesh governance features (model contracts, access modifiers, groups, versioning) and multi-project collaboration with cross-project refs. Use… official

upstash-workflow-js upstash

Lightweight guidance for using the Upstash Workflow SDK to define, trigger, and manage workflows. Use this Skill whenever a user wants to create workflow… official

run-acceptance-tests hashicorp

Guide for running acceptance tests for a Terraform provider. Use this when asked to run an acceptance test or to run a test with the prefix TestAcc. official

Playwright Skill lackeyjb

Enables Claude to write and execute any Playwright automation on-the-fly - from simple page tests to complex multi-step flows. development

firecrawl-parse firecrawl

Turn a local document into clean markdown on disk. Supports PDF, DOCX, DOC, ODT, RTF, XLSX, XLS, HTML/HTM/XHTML . official

skypilot-multi-cloud-orchestration firecrawl

Multi-cloud orchestration for ML workloads with automatic cost optimization. Use when you need to run training or batch jobs across multiple clouds, leverage… official