Playwright mock slow network request

mock.ts

const urlPattern = "**/some_endpoint";
const delayMS = 1000

await page.route(urlPattern, async (route) => {
  const resolve = (route: Route) => route.continue();
  const res = new Promise(() => resolve);

  setTimeout(async () => {
    await resolve(route);
  }, delayMS);

  return await res;
});