@fuf-stack/vitest-config

@fuf-stack/vitest-config

Default Vitest configurations for Fröhlich ∧ Frei monorepos. Provides separate configs for workspace-level (root) and project-level (package) setups.

Compatible with Vitest 4.0+

Configs Available

Workspace Config (/workspace) - For monorepo root:

• Projects array defining workspace structure
• V8 coverage with explicit includes/excludes
• LCOV reporter for CI tools

Project Config (/project) - For individual packages:

• TypeScript path mapping resolution
• Node environment by default
• Clear mocks between tests

Install

# pnpm
pnpm add -D @fuf-stack/vitest-config vitest @vitest/coverage-v8

# npm
npm i -D @fuf-stack/vitest-config vitest @vitest/coverage-v8

# yarn
yarn add -D @fuf-stack/vitest-config vitest @vitest/coverage-v8

Usage

Important: Use .mts extension for config files when importing this ESM-only package. Using .ts may cause bundler errors as tooling might attempt to use require() instead of import.

Workspace Root Config

Use the workspace config in your monorepo root vitest.config.mts:

// vitest.config.mts (root)
import config from '@fuf-stack/vitest-config/workspace';

export default config;

This provides:

• Projects array: ['apps/*', 'packages/!(config)', 'packages/config/*']
• Coverage configuration with sensible defaults
• LCOV reporter

packages/config is a container, not a test project. Its child packages are included individually so their tests run once under their own package names.

Customize if needed:

Use mergeConfig to adjust settings while retaining the default project discovery:

// vitest.config.mts
import { mergeConfig } from 'vitest/config';

import workspaceConfig from '@fuf-stack/vitest-config/workspace';

export default mergeConfig(workspaceConfig, {
  test: {
    testTimeout: 10_000,
  },
});

Add a project outside the default paths:

For an existing test project in tools/integration-tests, add its directory relative to the workspace root. mergeConfig concatenates arrays, so this extends projects while keeping the default app and package projects:

// vitest.config.mts
import { mergeConfig } from 'vitest/config';

import workspaceConfig from '@fuf-stack/vitest-config/workspace';

export default mergeConfig(workspaceConfig, {
  test: {
    projects: ['tools/integration-tests'],
  },
});

The directory can provide its own vitest.config.mts for project-specific settings.

Add inline projects and extra coverage paths:

The same applies to inline projects and to coverage.include / coverage.exclude: your entries are appended to the defaults. Don't spread the base config manually.

// vitest.config.mts
import { mergeConfig } from 'vitest/config';

import workspaceConfig from '@fuf-stack/vitest-config/workspace';

export default mergeConfig(workspaceConfig, {
  test: {
    projects: [
      {
        test: {
          name: 'scripts',
          include: ['scripts/**/*.test.mjs'],
          environment: 'node',
        },
      },
    ],
    coverage: {
      include: ['scripts/**/*.mjs'],
    },
  },
});

The default coverage excludes already match *.test.* / *.spec.* files of every JS/TS extension anywhere in the workspace, so extra includes don't need matching test excludes.

Package-Level Configs

Use the project config in individual package vitest.config.mts:

// packages/my-package/vitest.config.mts
import config from '@fuf-stack/vitest-config/project';

export default config;

This provides:

• TypeScript path mapping resolution (Vite native resolve.tsconfigPaths)
• Node environment (good for libraries, utilities)
• Clear mocks between tests

For React components (need jsdom):

// packages/ui-components/vitest.config.mts
import { mergeConfig } from 'vitest/config';

import projectConfig from '@fuf-stack/vitest-config/project';

export default mergeConfig(projectConfig, {
  test: {
    environment: 'jsdom',
    setupFiles: ['./vitest.setup.ts'],
  },
});

Migration from Vitest 3.x

1. Root config: Use /workspace import
2. Package configs: Use /project import (or customize with mergeConfig)
3. Rename config files: Change .ts → .mts (required for ESM-only packages)
4. Remove vitest.workspace.ts file
5. Ensure each package uses defineProject() (handled by /project config)

Why .mts Extension?

This package is ESM-only ("type": "module"). When Vitest bundles config files:

• .ts files are ambiguous - bundlers may try require() ❌
• .mts explicitly declares ES Module - uses import ✅

Using .ts may result in errors like:

Error: Cannot use import statement outside a module

The .mts extension tells tooling to treat the file as an ES Module, allowing proper imports of ESM-only dependencies.

Scripts

{
  "scripts": {
    "test": "vitest",
    "test:coverage": "vitest --coverage"
  }
}

License

MIT