Vitest

This is a prioritized collection of 44 Vitest testing rules organized into eight categories, from critical async patterns and test isolation down to lower priority concerns like test organization. What makes it useful is the explicit priority system: you know to fix async await issues and mock cleanup before worrying about snapshot formatting. It covers the tricky parts like vi.mock hoisting behavior, choosing between spyOn and mock, and performance tuning with pools and sharding. The quick reference table lets you scan by impact level, which beats scrolling through alphabetical lists when you're debugging flaky tests at 3pm. If you're migrating from Jest or trying to speed up your CI pipeline, the performance and mocking sections are worth reading first.

skills.sh installs: 7.2K
GitHub stars: 222
last updated: Aug 21, 2026

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Install

$ npx -y skills add pproenca/dot-skills --skill vitest --agent claude-code

Installs into .claude/skills of the current project.

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Vitest Best Practices

Comprehensive performance optimization and best practices guide for Vitest testing framework. Contains 44 rules across 8 categories, prioritized by impact to guide test writing, refactoring, and code review.

When to Apply

Reference these guidelines when:

Writing new Vitest tests
Debugging flaky or slow tests
Setting up test configuration
Reviewing test code in PRs
Migrating from Jest to Vitest
Optimizing CI/CD test performance

Rule Categories by Priority

Priority	Category	Impact	Prefix
1	Async Patterns	CRITICAL	`async-`
2	Test Setup & Isolation	CRITICAL	`setup-`
3	Mocking Patterns	HIGH	`mock-`
4	Performance	HIGH	`perf-`
5	Snapshot Testing	MEDIUM	`snap-`
6	Environment	MEDIUM	`env-`
7	Assertions	LOW-MEDIUM	`assert-`
8	Test Organization	LOW	`org-`

Vitest

Install

Files

Vitest Best Practices

When to Apply

Rule Categories by Priority

Quick Reference

1. Async Patterns (CRITICAL)

Details

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