[morinokami]

vp test stops with a startup error before it runs any test in a Void app on the default Cloudflare target. A fresh app shows it with a single expect(1).toBe(1) test:

npm create void@latest my-app -- --toolchain vite-plus --framework react --starter sqlite --deploy none --no-git

ReferenceError: module is not defined
    at runInRunnerObject (./workers/runner-worker/index.js:107:3)
    at getWorkerEntryExportTypes (./workers/runner-worker/index.js:252:24)

With nodejs_compat, which Void also turns on for apps that use auth, PostgreSQL, MySQL or Sandbox, and for TanStack Start, React Router and vinext apps:

Error: AssertionError: depsOptimizer is required in dev mode

vp dev works. Vitest loads vite.config.ts and starts a Vite server of its own, so the Cloudflare Vite plugin that voidPlugin() includes starts the Worker there too. Vitest turns off dependency prebundling in nearly every environment of that server, the Worker's included, and the Cloudflare plugin relies on it in development: a CommonJS dependency such as React reaches workerd unconverted, and with nodejs_compat the plugin's own polyfill import asserts on the missing optimizer. Users can't remove the plugin, and test.deps.optimizer doesn't bring dependency discovery back. The only workaround was a vitest.config.ts without voidPlugin(), which loses @schema and Void's generated modules, so the starter's pages/index.server.ts can't be imported.

Vitest's server also ran dev-server work. Each vp test applied local migrations, for PostgreSQL and MySQL to the database in .env, and in an app that uses AI without a linked project it would start the interactive project setup in a terminal.

Fix

isVitestServer() recognizes the server that Vitest creates by the plugins Vitest adds to it (vitest:*). In that server:

• The plugins of Void's Cloudflare wrapper, the Cloudflare Vite plugin included, don't apply, in Void apps and in TanStack Start, React Router and vinext apps. Void's other plugins still resolve void/*, @schema and the generated modules, so tests can import route handlers and page loaders.
• migrationPlugin doesn't apply.
• The AI project setup prints its hint instead of prompting.

Code generation, types and warnings stay as they are. Tests run in Node.js, so a call that reaches a binding still throws env: Cloudflare env is unavailable. Running tests in workerd with real bindings, as @cloudflare/vitest-plugin does for plain Workers, would need Void's generated entry, inferred bindings and migrations in the test runtime, and is left for later.

Vite passes each plugin's apply the config of the server it resolves, Vitest's plugins included, so the check works in any --mode and only for Vitest's own server. The alternatives fail in worse directions:

Check	Misses	Wrongly matches
process.env.VITEST	Servers from Vitest's API: createVitest() doesn't set it	Every server in the process, such as a dev server that a test starts, and Void's own Cloudflare plugin tests
mode === 'test'	vitest --mode staging	vp dev --mode test, which would lose the Worker
Vitest's plugin names	A future rename, which falls back to today's error	None found

The check also accepts the plugin named vitest that Vitest 3.2.4 and 4.0.0 add. The integration test below fails if a later Vitest renames these plugins, and packages/void/AGENTS.md asks to check the names when updating Vitest.

Docs

• A Testing guide under Development & Deployment: vp test needs no configuration, test APIs come from vite-plus/test (vitest with the Vite toolchain), test files stay out of convention directories (a test file in routes/ becomes a route), and vi.mock() replaces a binding module, since bindings aren't available in tests.
• The email testing examples import from vite-plus/test and link to the guide.
• The Void skill lists the guide, and TESTING.md mentions the packed vp test check.

Tests

• Unit: isVitestServer(); the Cloudflare wrapper resolved with and without Vitest's plugins, in modes test and staging; migrationPlugin in real dev servers; and the AI setup prompt.
• Integration: packages/void/test/integration/vitest-app.test.ts runs vp test run in isolated copies of playground/react-pages, first as is and then with nodejs_compat and --mode staging, and of playground/tanstack-start. It checks that no migration runs and no local D1 database appears. Without this fix, it fails with both errors above.
• Packed consumer: the Vite+ fixtures run vp test run on the guide's vi.mock('void/kv') example and a page loader import. Because this changes the packed script, this PR runs the full packed suite.

Verification

• vp test run: 790 files pass, 1 skipped (16,479 tests pass, 30 skipped).
• vp run check: 33/33 pass.
• vp run build:docs passes.
• By hand: vp test run passes in copies of the TanStack Start, React Router, vinext and SvelteKit playgrounds. In a copy of playground/react-pages, the guide's vi.mock('void/kv') example and the email testing example pass with vp test run and with plain vitest run, and no local D1 database appears. vp dev still serves / and /api/health and applies the migration.
• By hand on an app scaffolded from the packed tarballs with the command above (Vite+ 1.5.0, Vitest 5.1.0): vp test run passes with and without nodejs_compat.
• Not run: the packed consumer script locally. On my machine, the interactive void init stalled in its PTY while installing dependencies, before the new step.

🤖 Generated with Claude Code

[cpojer]

Thank you!