vitest/docs/config/alias.md

title, outline

title	outline
alias | Config	deep

alias

• Type: Record<string, string> | Array<{ find: string | RegExp, replacement: string, customResolver?: ResolverFunction | ResolverObject }>

Define custom aliases when running inside tests. They will be merged with aliases from resolve.alias.

::: warning Vitest uses Vite SSR primitives to run tests which has certain pitfalls.

1. Aliases affect only modules imported directly with an import keyword by an inlined module (all source code is inlined by default).
2. Vitest does not support aliasing require calls.
3. If you are aliasing an external dependency (e.g., react -> preact), you may want to alias the actual node_modules packages instead to make it work for externalized dependencies. Both Yarn and pnpm support aliasing via the npm: prefix. :::