Made of little things.

// Trusted local scenario: players who press Play public at once can each open a room;
// lone players then consolidate into one room without leaving the drive.
export default async ({players,check}) => {
  const waitFor = (player, fn, arg, timeout) => player.frame.waitForFunction(fn,arg,{timeout});
  await Promise.all(players.map(p => p.frame.getByRole('button',{name:'Play public',exact:true}).click()));
  await Promise.all(players.map(p => waitFor(p,()=>!!document.querySelector('canvas')?.dataset.localPosition,undefined,30000)));
  check('every player is driving', true);
  await Promise.all(players.map(p => waitFor(p,n=>Number(document.querySelector('canvas')?.dataset.onlinePlayers)===n,players.length,60000)));
  check('simultaneous players end up in one public room', true);
};