Blockchain By Example

Time manipulation

In a separate file, called increaseTime.js, within the test/ directory, define the following module to move time forward for a given duration:

module.exports.increaseTime = function increaseTime(duration) {  const id = Date.now();  return new Promise((resolve, reject) => {    web3.currentProvider.sendAsync({      jsonrpc: "2.0",      method: "evm_increaseTime",      params: [duration],      id: id    }, err1 => {       if (err1) {        return reject(err1);      }      web3.currentProvider.sendAsync({        jsonrpc: "2.0",        method: "evm_mine",        id: id + 1      }, (err2, res) => {        return err2 ? reject(err2) : resolve(res);      });    });  });};

Don’t let this strange chunk of code fool you. It is actually very easy to read and understand, so have a second look.

To understand what's going on, ...