Vitest Knowledge Patch (3.0 – 4.1)

Supplementary knowledge for Vitest features released after Claude's training cutoff. Covers versions 3.0 through 4.1 (January 2025 – March 2026).

Reference Files

• references/projects-config.md — workspace replaced by projects, inline config, sequence.groupOrder, watchTriggerPatterns, defineProject
• references/browser-mode.md — Stable browser mode (v4), provider packages, locators, visual regression testing, Playwright traces, frame locators
• references/test-fixtures-hooks.md — Scoped fixtures, test.extend builder pattern, aroundEach/aroundAll hooks, type-aware hooks, vi.defineHelper, test signal API
• references/matchers-mocking.md — expect.assert, expect.schemaMatching, Matchers type, mockThrow, using with vi.spyOn/fn, v4 mocking changes
• references/test-organization.md — Test tags (v4.1), test annotations, agent reporter, GitHub Actions job summary, --detect-async-leaks
• references/migration-v4.md — Breaking changes, coverage overhaul, simplified exclude, viteModuleRunner: false, Node.js 20+ requirement

Projects (replaces Workspace)

The workspace config and separate vitest.workspace files are deprecated (v3.2) and removed in v4. Use projects instead: