export function advanceBlock () {
  return new Promise((resolve, reject) => {
    web3.currentProvider.sendAsync({
      jsonrpc: '2.0',
      method: 'evm_mine',
      id: Date.now(),
    }, (err, res) => {
      return err ? reject(err) : resolve(res);
    });
  });
}

// Advances the block number so that the last mined block is `number`.
export default async function advanceToBlock (number) {
  if (web3.eth.blockNumber > number) {
    throw Error(`block number ${number} is in the past (current is ${web3.eth.blockNumber})`);
  }

  while (web3.eth.blockNumber < number) {
    await advanceBlock();
  }
}