vitest-dev/vitest · error · Error

Cannot parse '${url}' because "module.stripTypeScriptTypes"

Error message

Cannot parse '${url}' because "module.stripTypeScriptTypes" is not supported. TypeScript coverage requires Node.js 22.15 or higher. This is NOT a bug of Vitest.

What it means

When instrumenting TypeScript files for coverage, vitest strips types via Node's module.stripTypeScriptTypes (coverage.ts:743). That API only exists in Node.js 22.15+, so older Node crashes here. The error message is explicit that this is an environment limitation, not a vitest bug.

Source

Thrown at packages/vitest/src/node/coverage.ts:743

  // TODO: should this be abstracted in `project`/`vitest` instead?
  // if we decide to keep `viteModuleRunner: false`, we will need to abstract transformation in both main thread and tests
  // custom --import=module.registerHooks need to be transformed as well somehow
  async transformFile(url: string, project: TestProject, viteEnvironment: string, isTransformedByVite = true): Promise<TransformResult | null | undefined> {
    const config = project.config

    // vite is disabled, should transform manually if possible
    if (config.experimental.viteModuleRunner === false || !isTransformedByVite) {
      const pathname = url.split('?')[0]
      const filename = pathname.startsWith('file://') ? fileURLToPath(pathname) : pathname
      const extension = path.extname(filename)
      const isTypeScript = extension === '.ts' || extension === '.mts' || extension === '.cts'
      if (!isTypeScript) {
        const code = await fs.readFile(filename, 'utf-8')
        return { code, map: null }
      }
      if (!module.stripTypeScriptTypes) {
        throw new Error(`Cannot parse '${url}' because "module.stripTypeScriptTypes" is not supported. TypeScript coverage requires Node.js 22.15 or higher. This is NOT a bug of Vitest.`)
      }
      const isTransform = process.execArgv.includes('--experimental-transform-types')
        || config.execArgv.includes('--experimental-transform-types')
        || process.env.NODE_OPTIONS?.includes('--experimental-transform-types')
        || config.env?.NODE_OPTIONS?.includes('--experimental-transform-types')
      const code = await fs.readFile(filename, 'utf-8')
      return {
        // `transform` mode will inject source maps comment at the end
        code: module.stripTypeScriptTypes(code, { mode: isTransform ? 'transform' : 'strip' }),
        map: null,
      }
    }

    return project.vite.environments[viteEnvironment].transformRequest(url)
  }

  createUncoveredFileTransformer(ctx: Vitest) {
    const projects = new Set([

View on GitHub (pinned to d568f8ce37)

Solutions

1. Upgrade Node.js to 22.15 or newer.
2. Run Node with --experimental-transform-types (and set NODE_OPTIONS accordingly) so stripTypeScriptTypes is available in transform mode.
3. Downgrade vitest to a version that didn't require stripTypeScriptTypes, or exclude .ts from coverage.

Example fix

// before
"engines": { "node": ">=20" } // CI uses Node 20 -> throws on .ts coverage

// after
"engines": { "node": ">=22.15" }
// CI image: node:22

import { gte } from 'semver'
if (gte(process.version, 'v22.15.0') === false) {
  throw new Error(`TypeScript coverage needs Node >=22.15; current ${process.version}`)
}

function supportsStripTypeScriptTypes(): boolean {
  return typeof (require('node:module') as any).stripTypeScriptTypes === 'function'
}

When it happens

Trigger: Running vitest coverage over .ts/.mts/.cts files with coverage enabled on a Node.js version older than 22.15.

Common situations: CI pinned to Node 20 LTS; local dev on Node 18/20; upgrading vitest without upgrading Node.

Related errors

• Cannot parse '${filename}' because "module.stripTypeScriptTy
• Cannot parse '${filename}' because "module.stripTypeScriptTy
• toHaveFormValues must be called with an object of expected f
• Not called in the browser
• The "${name}" browser provider does not provide a "providerF

AI-assisted analysis of vitest-dev/vitest@d568f8ce37 (2026-08-03). Data as JSON: /data/errors/c814e7fa17d9c3ac.json. Report an issue: GitHub.