Vite dev server

This page assumes the forwarder and the test helper change from Common setups, and that pnpm test:dev from Holodeck in dev mode starts holodeck next to Vite. The plugin was tested on Node 26.10 and Vite 8.3.

Add the plugin

In your Vite config, vite.config.mjs in an app from Ember's blueprint, import the forwarder and put this plugin first in the plugins array you already have.

import { forwardToHolodeck } from './forward-to-holodeck.mjs';

export default defineConfig({
  plugins: [
    {
      name: 'holodeck',
      apply: 'serve',
      configureServer(server) {
        server.middlewares.use(forwardToHolodeck());
      },
    },
    // your other plugins
  ],
});

apply: 'serve' keeps it out of builds. configureServer runs before Vite's own middleware, so holodeck's requests never reach a server.proxy entry you may have for /api.

Run it

1. Run pnpm test:dev.
2. Open http://localhost:4200/tests.

The suite passes, and every request in the network panel goes to http://localhost:4200, with no OPTIONS among them. In a test app with 17 tests and one DELETE, that is 208 requests instead of the 209 the cross-origin page makes, the missing one being the preflight for that DELETE. The first load after you change the Vite config can sit at 0 / N tests completed while Vite re-optimizes dependencies. Reload the page.

Related

• Testem does the same for pnpm test, with the same forwarder.
• Caddy puts an HTTPS origin in front of this one.
• Holodeck in dev mode starts holodeck next to the dev server.