openzeppelin-contracts/test/helpers/timer.js

// timer for tests specific to testrpc
module.exports = s => {
  console.log('timer to', s);
  return new Promise((resolve, reject) => {
    web3.currentProvider.sendAsync({
      jsonrpc: '2.0', 
      method: 'evm_increaseTime',
      params: [s], // 60 seaconds, may need to be hex, I forget
      id: new Date().getTime() // Id of the request; anything works, really
    }, function(err) {
      console.log('resolved to', err);
      if (err) return reject(err);
      resolve();
    });
    //setTimeout(() => resolve(), s * 1000 + 600) // 600ms breathing room for testrpc to sync
  });
};