https://twitter.com/dnwiebe/status/1085285472274915330

example.js

/*
 * testing involving real time is an integration test - high value, high cost
 * these next two routines represent that interface
 */
const msDeadline= ms=> {
  console.log('msDeadline',ms);
  const deadline= ms+new Date().getTime();
  return ()=>deadline < new Date().getTime();
};

const msDelay= ms=> {
  console.log('msDelay',ms);
  return new Promise(resolve => setTimeout(resolve, ms));
}

/*
 * you'll want something different:
 */
const tryToConnect= ()=> {
  const n= Math.random();
  console.log('tryToConnect',n);
  return 0.1 > n;
}
  
/*
 * Try to connect every 250ms for two seconds,
 * and return me a Promise. If you connect,
 * resolve the Promise with true, if you fail until
 *  timeout, resolve it with false.
 */
const promiseToConnect= async ()=> {
  const pastDeadline= msDeadline(2000);
  do {
    if (tryToConnect()) return true;
    await msDelay(250);
  } while (!pastDeadline());
  return false;
}

/*
 * test jig
 */
let p= promiseToConnect();
p.then((ok)=>console.log('done', ok));