evOo-local/packages/testkit/src/fake-kokoro.ts

import { createServer } from "node:http";
import type { AddressInfo } from "node:net";

/**
 * Stands in for the local Kokoro speech server so onboarding's voice step never depends on
 * whatever happens to listen on the default port of the machine running the suite.
 */
export async function startFakeKokoro(): Promise<{ baseUrl: string; close: () => Promise<void> }> {
  const server = createServer((req, res) => {
    if (req.method === "GET" && req.url === "/v1/audio/voices") {
      res.writeHead(200, { "content-type": "application/json" });
      // An empty list makes the adapter fall back to its curated presets.
      res.end(JSON.stringify({ voices: [] }));
      return;
    }
    if (req.method === "POST" && req.url === "/v1/audio/speech") {
      req.resume();
      req.on("end", () => {
        // An MPEG frame header is enough for callers that only check the content type.
        res.writeHead(200, { "content-type": "audio/mpeg" });
        res.end(Buffer.from([0xff, 0xfb, 0x90, 0x64, 0, 0, 0, 0]));
      });
      return;
    }
    res.writeHead(404).end();
  });
  await new Promise<void>((resolve) => server.listen(0, "127.0.0.1", resolve));
  const { port } = server.address() as AddressInfo;
  return {
    baseUrl: `http://127.0.0.1:${port}`,
    close: () => new Promise((resolve) => server.close(() => resolve())),
  };
}