Cannot read property 'getBlock' of undefined

Question

I'm having an issue with running truffle test on a Javascript test. I get the error TypeError: Cannot read property 'getBlock' of undefined.

I am trying to get the time of the latest block by using a snippet from OpenZeppelin:

async function latestTime () {
  const block = await web3.eth.getBlock('latest');
  return block.timestamp;
}

When I run this in truffle console, web3.eth.getBlock('latest') works fine.

Answer 1

The error message implies that web3.eth has not been defined in your JavaScript context.

Make sure you are also including the code which adds the web3 provider:

window.addEventListener('load', function() {

  // Checking if Web3 has been injected by the browser (Mist/MetaMask)
  if (typeof web3 !== 'undefined') {
    // Use Mist/MetaMask's provider
    web3 = new Web3(web3.currentProvider);
  } else {
    console.log('No web3? You should consider trying MetaMask!')
    // fallback - use your fallback strategy (local node / hosted node + in-dapp id mgmt / fail)
    web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));
  }

  // Now you can start your app & access web3 freely:
  startApp()

})

From here: Web3 - Ethereum Browser Environment Check

EDIT: For developing in truffle, the code would look something like this:

  initWeb3: function () {
    // Is there an injected web3 instance?
    if (typeof web3 !== 'undefined') {
      App.web3Provider = web3.currentProvider;
    } else {
      // If no injected web3 instance is detected, fall back to Ganache
      App.web3Provider = new Web3.providers.HttpProvider('http://localhost:7545');
    }
    web3 = new Web3(App.web3Provider);

    return App.initContract();
  },

Answer 2

My issue was a versioning problem truffle console was running web3 1.0 while my tests were accessing an injected web3 0.20 instance. This mean that when I ran my test in an interactive console, it would succeed, but obviously fail when I ran it using truffle test.